Imaging tools in rheumatoid arthritis: ultrasound vs magnetic resonance imaging

An update on thermal imaging in rheumatoid arthritis

This review aims to summarise the recent literature concerning the usage of thermal imaging in the study of rheumatoid arthritis (RA). Most RA studies have applied thermal imaging as a static process alone although thermal imaging has been conducted with an additional dynamic/functional component. Algorithms to automate the analysis of thermal imaging in RA have also been described. Several RA thermal imaging studies have demonstrated differences in thermographic findings between RA patients and healthy controls and/or compared thermographic parameters with other clinical/functional/imaging parameters; while fewer studies have assessed the role of thermal imaging in discriminating disease severity in RA. Thermal imaging is a relatively low cost, non-invasive imaging technique offering an objective measurement of joint surface temperature in RA joint inflammation assessment. Although there has been an increasing literature build up on the use of thermography in RA, more validation work is still necessary to delineate the potential role(s) of its use among patients with RA. This timely review focusses on the recent literature concerning thermal imaging, and provides clinicians with an update on its recent development in RA.

Comparison of High-Resolution Ultrasonography With Magnetic Resonance Imaging in Rheumatoid Arthritis

Objective:

The aim of this study was to examine whether high-resolution ultrasonography (HRUS) can provide information, on signs of inflammation and destruction, due to rheumatoid arthritis (RA). The focus was on the wrist joint, during early and late disease and compared the findings to those with magnetic resonance imaging (MRI).

Materials and Methods:

The study was based on 31 RA patients, with joint involvements, who were selected from those attending the outpatient rheumatology clinic. The patients completed both HRUS and MRI examinations, and their results were compared.

Results:

The HRUS and MRI images had near-perfect agreement, for detecting joint anomalies, in those RA patients. While comparing the overall performance of the HRUS and MRI studies, it was observed that HRUS was equal or nearly equal, demonstrating 90.83%, 100.0% and 94.93%, diagnostic sensitivity, specificity, and accuracy, respectively, for diagnosing RA pathologies.

Conclusion:

The early diagnosis of RA with HRUS and MRI examinations is very important, in the early treatment of RA. The HRUS examinations demonstrated a sensitive and reliable diagnostic method for assessing inflammatory activity and destructive changes in the joints of these RA patients, with HRUS findings comparable to those of MRI.

Prediction of flare following remission and treatment withdrawal in early rheumatoid arthritis: post hoc analysis of a phase IIIb trial with abatacept

Background

Drug-free remission is a desirable goal in rheumatoid arthritis (RA) for both patients and clinicians. The aim of this post hoc analysis was to investigate whether clinical and magnetic resonance imaging (MRI) variables in patients with early RA who achieved remission with methotrexate and/or abatacept at 12 months could predict disease flare following treatment withdrawal.

Methods

In the AVERT study of abatacept in early RA, patients with low disease activity at month 12 entered a 12-month period with all treatment discontinued (withdrawal, WD). This post hoc analysis assessed predictors of disease flare at WD+6months (mo) and WD+12mo of patients with Disease Activity Score in 28 joints (DAS28)-defined remission (DAS28[C-reactive protein (CRP)] <2.6) at withdrawal using univariate and multivariable regression models. Predictors investigated included the Health Assessment Questionnaire–Disability Index (HAQ-DI), pain, Patient Global Assessment; MRI synovitis, erosion, bone edema, and combined (synovitis + bone edema) inflammation scores.

Results

Remission was achieved by 172 patients; 100 (58%) and 113 (66%) patients had experienced a flare at WD+6mo and WD+12mo, respectively. In univariate analyses, higher HAQ-DI and MRI synovitis, erosion, bone edema, and combined inflammation scores at WD were identified as potential predictors of flare (P ≤ 0.01). In multivariable analysis, high scores at WD for HAQ-DI and MRI erosion were confirmed as independent predictors of flare at WD+6mo and WD+12mo (P < 0.01).

Conclusion

In patients with early RA achieving clinical remission, patient function (HAQ-DI), and MRI measures of bone damage (erosion) predicted disease flare 6 and 12 months after treatment withdrawal. These variables may help identify patients with early RA in clinical remission as candidates for successful treatment withdrawal.

Trial registration

ClinicalTrials.gov, NCT01142726 (date of registration: June 11, 2010)

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02735-8.

Anti-Cyclic Citrullinated Peptide Antibodies Correlate to Ultrasound Synovitis in Rheumatoid Arthritis Better Than C-Reactive Protein

OBJECTIVES

The aim of this study was to compare ultrasound (US) grading and laboratory measures in patients with rheumatoid arthritis.

METHODS

Two-hundred four patients with rheumatoid arthritis who received US evaluation for synovitis were included after excluding those using tocilizumab. Ultrasound grading of synovial hypertrophy (SH) and power Doppler (PD) at the most severe site were recorded. An assessment of the correlation of laboratory measures and US grading was conducted by reviewing the electronic medical records.

RESULTS

High-titer anti-cyclic citrullinated peptide (anti-CCP) antibodies positivity was associated with SH grade ≥2 (odds ratio [OR], 6.00; 95% confidence interval [CI], 1.78-20.2) and PD grade ≥2 (OR, 5.56; 95% CI, 1.82-16.9). Recent C-reactive protein (CRP) levels ≥0.3 mg/dL were associated with SH grade ≥2 (OR, 3.13; 95% CI, 1.38-7.10) and PD grade ≥2 (OR, 2.38; 95% CI, 1.31-4.31). Anti-CCP antibody levels correlated with US scores better than the levels of CRP with higher Spearman ρ correlation coefficients. Most of the patients with recent CRP levels <0.3 mg/dL had US synovitis. In logistic regression, high levels of anti-CCP antibodies and CRP were both independently associated with SH grade ≥2 and PD grade ≥2.

CONCLUSIONS

Higher levels of anti-CCP antibodies and CRP may predict synovitis on US, whereas discrepancies existed between inflammatory markers and US grading. These findings suggest that US has a role in the comprehensive assessment of disease activity, especially for patients with high-titer positive anti-CCP antibodies.

Measuring Inflammatory Foot Disease in Rheumatoid Arthritis: Development and Validation of the Rheumatoid Arthritis Foot Disease Activity Index-5

OBJECTIVE

Omission of foot joints from composite global disease activity indices may lead to underestimation of foot and overall disease in rheumatoid arthritis (RA) and under-treatment. The aim of this study was to evaluate the measurement properties of the Rheumatoid Arthritis Foot Disease Activity Index-5 (RADAI-F5), a newly developed patient-reported outcome measure for capturing foot disease activity in people with RA.

METHODS

Participants with RA self-completed the RADAI-F5, modified Rheumatoid Arthritis Disease Activity Index (mRADAI-5), Foot Function Index (FFI), and Foot Impact Scale (FIS) impairment/footwear and activity/participation subscales. The 28-joint Disease Activity Score using the erythrocyte sedimentation rate (DAS28-ESR) was also recorded. Subgroups completed the RADAI-F5 at 1 week and 6 months. Psychometric properties, including construct, content and longitudinal validity, internal consistency, 1-week reproducibility, and responsiveness over 6 months were evaluated.

RESULTS

Of 142 respondents, 103 were female, with a mean ± SD age of 55 ± 12.5 years and median RA disease duration of 10 (interquartile range 3.6-20.8) months. Theoretically consistent associations confirming construct validity were observed with mRADAI-5 (0.789 [95% confidence interval (95% CI) 0.73, 0.85]), FFI (0.713 [95% CI 0.62, 0.79]), FIS impairment/footwear (0.695 [95% CI 0.66, 0.82], P < 0.001), FIS activity/participation (0.478 [95% CI 0.37, 0.63], P < 0.001), and the DAS28-ESR (0.379 [95% CI 0.26, 0.57], P < 0.001). The RADAI-F5 demonstrated high internal consistency (Cronbach's α = 0.90) and good reproducibility (intraclass correlation coefficient = 0.868 [95% CI 0.80, 0.91], P < 0.001, smallest detectable change = 2.69). Content validity was confirmed, with 82% rating the instrument relevant and easy to understand.

CONCLUSION

The RADAI-F5 is a valid, reliable, responsive, clinically feasible patient-reported outcome measure for measuring foot disease activity in RA.

The changing role of ultrasonography examination in patients with rheumatoid arthritis in light of recent studies

For many years, ultrasonography (US) has been a widely accepted modality used for joint assessment in patients with rheumatoid arthritis (RA). Given the efficacy of present day therapies, there is scepticism whether it is required in the first place. The most recent clinical Targeting synovitis in Early Rheumatoid Arthritis (TaSER) and Clinical Tight Control Therapy (ARCTIC) trials’ results appear to contradict it, yet this does not necessarily mean ultrasound has no place in modern rheumatology. The possibility of detecting inflammation at a subclinical level carries a tremendous predictive value, enabling identification of patients likely to experience an exacerbation in the coming months. Therefore, US should be a part of the decision-making process regarding treatment modification or introduction of any additional interventions, such as glucocorticosteroid injections.

The results of the most recent clinical trials do not negate the usefulness of US, but merely suggest that it ought to be used in moderation.

Fluorometric Imaging for Early Diagnosis and Prognosis of Rheumatoid Arthritis

Early diagnosis and monitoring of disease progress are of significant importance in the effective treatment of rheumatoid arthritis (RA), because the continuing inflammation can lead to irreversible joint damage and systemic complications. However, applying imaging modalities for the prognosis of RA remains challenging, because no tissue-specific guidelines are available to monitor the progressive course of RA. In this study, fluorometric imaging of RA is reported using bioengineered targeted agents of the blood vessel, bone, and cartilage in combination with the customized optical fluorescence imaging system. Separate but simultaneous tissue-specific images of synovitis, cartilage destruction, and bone resorption are obtained from a mouse model of RA, which allows quantification of the prognosis of diseases at each stage. Thus, the fluorometric imaging of RA by using tissue-specific contrast agents plays a key role in the systemic treatment of RA by monitoring structural damage and disease progression.

Early Diagnosis Of Inflammatory Arthritis By Primary Care Physicians Following Training By A Rheumatologist

Background

Early diagnosis and therapeutic management of inflammatory arthritis (IA) is crucial for minimizing disease progression and improving outcomes. We recently developed the New Early Arthritis Referral Criteria to help improve the detection of suspected early IA via musculoskeletal (MSK) examination. The present study aimed to evaluate the agreement between rheumatologists and primary care physicians (PCPs) trained by rheumatologists in detecting IA when applying the standardized MSK examination techniques used to develop this criteria in a real-world setting in Jeddah, Saudi Arabia.

Methods

This quasi-experimental study was conducted in 4 primary health centers and involved 30 PCPs and 3 rheumatologists. All PCPs were trained by rheumatologists to apply the standardized MSK examination techniques used to develop the New Early Arthritis Referral Criteria. Patients were eligible if they were >18 years of age and presented with small-joint pain that persisted for >6 weeks. Patients were excluded if they had prior diagnosis of osteoarthritis, hand fractures, or rheumatic disease associated with IA. All patients were examined separately by a PCP and a rheumatologist, with the findings compared via kappa statistics and the rheumatologist’s findings considered the “gold standard”.

Results

Data from 202 of the 203 enrolled patients were analyzed. There was fair-to-moderate agreement between PCPs and rheumatologists when assessing swelling of the small joints and wrist of the right side (range of kappa: 0.14–0.41) and low-to-moderate agreement in similar examinations of the left side (range of kappa: 0.04–0.42). Assessments of joint tenderness showed fair-to-moderate agreement for both the right side (range of kappa: 0.22–0.47) and left side (range of kappa: 0.24–0.45). P-values were significant for virtually all comparisons.

Conclusion

MSK examinations by PCPs showed a promising extent of agreement in detecting IA with those by rheumatologists following training. Refinement of the standardized training process could further improve accuracy and help PCPs to confidently identify cases of early IA, thus allowing earlier intervention than is typical in this setting.

Should ultrasound be used routinely in the diagnosis of rheumatoid arthritis?

INTRODUCTION

A growing body of evidence indicates the benefits of early diagnosis of rheumatoid arthritis (RA) and prompt treatment with disease-modifying anti-rheumatic drugs (DMARDS) in terms of relieving symptoms, improving prognosis, and reducing long-term complications. There is however some controversy over the most beneficial method of imaging in providing accurate early diagnosis. Though current practice favours clinical and radiological assessment, this is increasingly supplemented by ultrasound techniques (and, to a lesser extent, CT and MRI scanning). While EULAR and ESSR favour the use of ultrasonography (US) as the first-line investigation in cases of suspected RA, a recent NICE review upholds the traditional place of plain film radiographs of hands and feet to detect erosions as early signs of synovitis. This review considers the evidence for US in the early diagnosis of RA and the case for it becoming the primary assessment modality in rheumatology clinics.

AIMS

This paper aims to assess the current literature on the efficacy of ultrasonography in diagnosing early RA, by comparing US with alternative imaging modalities. The goal is to propose the most appropriate method of diagnosis to improve early initiation of DMARD treatment for optimum disease outcomes.

METHODS

Searches for related studies and review articles were carried out using electronic databases and hand searches. Additional references were gleaned from the bibliographies of included papers. Related articles and pop-outs from PubMed were also used. The search was refined in PubMed, by only using reviews which were written in English and published in past 10 years and had full free text available.

RESULTS

This review confirms that US has a high level of sensitivity in diagnosing RA (and hence a low risk of missing cases of RA which might benefit from early treatment with DMARDs). It also has a high level of specificity (and hence a low risk of falsely diagnosing somebody with RA who may suffer adverse effects of DMARD therapy). US is already widely available and well accepted by clinicians and patients. It does not involve exposure to radiation and can be readily delivered by appropriately trained staff.

CONCLUSION

This review of relevant studies indicates that US should become accepted as the investigation with the most favourable balance of benefits to risks in the early diagnosis of RA. Given the continuing controversy surrounding studies of different imaging techniques in RA, further research into the diagnostic role of US in RA is indicated.

Sonography of active rheumatoid arthritis during pregnancy: a case report and literature review

Disease activity in rheumatoid arthritis usually subsides in pregnancy, however a subset of patients have worsened symptoms with joint pain and swelling. Monitoring and mitigating disease activity in pregnancy is important for preventing deforming structural changes which can affect the ability of the patient to care for themselves and the newborn. Ultrasound is a safe and low-cost imaging modality for detecting active changes from an inflammatory arthritis, which can help guide management. We describe a case of an acute disease flare during pregnancy, readily detected with ultrasound, and present a review of sonographic evaluation of rheumatoid arthritis in pregnancy.

Inflammatory arthritis and crystal arthropathy: Current concepts of skin and systemic manifestations

Systemic inflammatory disorders frequently involve the skin, and when cutaneous disease develops, such dermatologic manifestations may represent the initial sign of disease and may also provide valuable prognostic information about the underlying disorder. Familiarity with the various skin manifestations of systemic disease is therefore paramount and increases the likelihood of accurate diagnosis, which may facilitate the implementation of an appropriate treatment strategy. An improvement in quality of life and a reduction in the degree of morbidity may also be a realized benefit of accurate recognition of these skin signs. With this context in mind, this review highlights the salient clinical features and unique dermatologic manifestations of rheumatoid arthritis, adult-onset Still's disease, and the crystal arthropathy, gout.

The Dorsal 4-finger Technique: A Novel Method to Examine Metacarpophalangeal Joints in Patients with Rheumatoid Arthritis

OBJECTIVE

To describe the dorsal 4-finger technique (DFFT) in examining metacarpophalangeal (MCP) joints of patients with rheumatoid arthritis (RA) and compare it to the traditional 2-finger technique (TFT) using ultrasound (US) as a gold standard.

METHODS

Four rheumatologists evaluated 180 MCP joints of 18 patients with RA. All patients underwent US for greyscale (GSUS) and power Doppler US (PDUS). Agreements between rheumatologists, the 2 techniques, and US were evaluated using Cohen κ and the first-order agreement coefficient (AC1) κ methods.

RESULTS

The population comprised 17 females (94.4%) with a mean (SD) age and disease duration of 56.8 (14.4) and 21.8 (12.9) years, respectively. Eight patients (44.4%) were taking methotrexate monotherapy, while 10 patients (55.6%) were receiving biologics. US evaluation revealed 69 (38.3%) and 30 (16.7%) joints exhibited synovitis grade 2-3 by GSUS and PDUS, respectively. Effusion was documented in 30 joints (16.7%). The mean intraobserver agreement using the DFFT and TFT were 80.5% and 86%, respectively. The mean interobserver agreements using the DFFT and TFT were 84% and 74%, respectively. κ agreement with US findings was similar for both techniques in tender joints but was higher for the DFFT in nontender joints (0.33 vs 0.07, p = 0.015 for GSUS) and (0.48 vs 0.11, p = 0.002 for PDUS). The DFFT had a higher sensitivity in detecting ballottement by GSUS (0.47 vs 0.2, p < 0.001) and PDUS (0.60 vs 0.27, p < 0.001).

CONCLUSION

The DFFT is a novel, reproducible, and reliable method to examine MCP joints, and it has a better correlation with US than the traditional TFT.

Targeting lymphatic function as a novel therapeutic intervention for rheumatoid arthritis

Although clinical outcomes for patients with rheumatoid arthritis (RA) have greatly improved with the use of biologic and conventional DMARDs, approximately 40% of patients do not achieve primary clinical outcomes in randomized trials, and only a small proportion achieve lasting remission. Over the past decade, studies in murine models point to the critical role of the lymphatic system in the pathogenesis and therapy of inflammatory-erosive arthritis, presumably by the removal of catabolic factors, cytokines and inflammatory cells from the inflamed synovium. Murine studies demonstrate that lymphatic drainage increases at the onset of inflammatory-erosive arthritis but, as inflammation progresses to a more chronic phase, lymphatic clearance declines and both structural and cellular changes are observed in the draining lymph node. Specifically, chronic damage to the lymphatic vessel from persistent inflammation results in loss of lymphatic vessel contraction followed by lymph node collapse, reduced lymphatic drainage, and ultimately severe synovitis and joint erosion. Notably, clinical pilot studies in patients with RA report lymph node changes following treatment, and thus draining lymphatic vessels and nodes could represent a potential biomarker of arthritis activity and response to therapy. Most importantly, targeting lymphatics represents an innovative strategy for therapeutic intervention for RA.

Detection of Subclinical Arthritis in Mice by a Thrombin Receptor-Derived Imaging Agent

OBJECTIVE

Functional imaging of synovitis could improve both early detection of rheumatoid arthritis (RA) and long-term outcomes. Given the intersection of inflammation with coagulation protease activation, this study was undertaken to examine coagulation protease activities in arthritic mice with a dual-fluorescence ratiometric activatable cell-penetrating peptide (RACPP) that has a linker, norleucine (Nle)-TPRSFL, with a cleavage site for thrombin.

METHODS

K/BxN-transgenic mice with chronic arthritis and mice with day 1 passive serum-transfer arthritis were imaged in vivo for Cy5:Cy7 emission ratiometric fluorescence from proteolytic cleavage and activation of RACPP_NleTPRSFL . Joint thickness in mice with serum-transfer arthritis was measured from days 0 to 10. The cleavage-evoked release of Cy5-tagged tissue-adhesive fragments enabled microscopic correlation with immunohistochemistry for inflammatory markers. Thrombin dependence of ratiometric fluorescence was tested by ex vivo application of RACPP_NleTPRSFL and argatroban to cryosections obtained from mouse hind paws on day 1 of serum-transfer arthritis.

RESULTS

In chronic arthritis, RACPP_NleTPRSFL fluorescence ratios of Cy5:Cy7 emission were significantly higher in diseased swollen ankles of K/BxN-transgenic mice than in normal mouse ankles. A high ratio of RACPP_NleTPRSFL fluorescence in mouse ankles and toes on day 1 of serum-transfer arthritis correlated with subsequent joint swelling. Foci of high ratiometric fluorescence localized to inflammation, as demarcated by immune reactivity for citrullinated histones, macrophages, mast cells, and neutrophils, in soft tissue on day 1 of serum-transfer arthritis. Ex vivo application of RACPP_NleTPRSFL to cryosections obtained from mice on day 1 of serum-transfer arthritis produced ratiometric fluorescence that was inhibited by argatroban.

CONCLUSION

RACPP_NleTPRSFL activation detects established experimental arthritis, and the detection of inflammation by RACPP_NleTPRSFL on day 1 of serum-transfer arthritis correlates with disease progression.

Diagnostic value of 18F-fluorodeoxyglucose uptake parameters to differentiate rheumatoid arthritis from other types of arthritis

We aimed evaluate F-fluorodeoxyglucose uptake at major joints for differentiating patients with rheumatoid arthritis (RA) from those with non-RA arthritis using F-fluorodeoxyglucose (FDG)-positron emission tomography (PET).Eighteen patients with RA (13 women; age, 66.8 ± 13.2 years) and 17 patients with non-RA (6 women; age, 50.8 ± 12.5 years) were included. Twelve joints of each patient were examined: shoulder, elbow, wrist, hip, knee, and ankle on both sides. A visual scoring (VS) system was used; quantitative parameters such as maximum standardized uptake value (SUVmax), metabolic active volume (MAV), and total lesion glycolysis (TLG) were evaluated. Total score and value of each parameter were compared between the RA and non-RA groups.Total VS score (mean, 37.7 ± 9.0 vs 21.9 ± 7.2; P < .0001) and SUVmax (mean, 28.1 ± 8.5 vs 17.9 ± 5.8; P < .001) were significantly higher in the RA group than in the non-RA group. A significant between-group difference was also observed with respect to total MAV (608.3 ± 370.7 vs 176.5 ± 217.8; P < .001) and total TLG (1139.3 ± 759.1 vs 289.5 ± 395.4; P < .001). Receiver operating characteristic curve analysis revealed that total VS had the highest area under curve (.92), with sensitivity and specificity of 88.9% and 76.4%, respectively.Quantitative PET parameters could differentiate RA from non-RA. Total VS score, however, appears to be the best convenient qualitative tool for diagnosing RA.

Determining early referral criteria for patients with suspected inflammatory arthritis presenting to primary care physicians: a cross-sectional study

Objective

Early diagnosis and initiation of treatment for inflammatory arthritis can greatly improve patient outcome. We aimed to provide standardized and validated criteria for use by primary care physicians (PCPs) in the identification of individuals requiring referral to a rheumatologist.

Patients and methods

We analyzed the predictive value of a wide variety of demographic variables, patient-reported complaints, physical examination results, and biomarkers in order to identify the most useful factors for indicating a requirement for referral. Patients for this cross-sectional study were enrolled from various centers of the city of Jeddah, Saudi Arabia, if they were ≥18 years of age and presented to a PCP with small joint pain that had been present for more than 6 weeks. A total of 203 patients were enrolled, as indicated by the sample size calculation. Each patient underwent a standardized physical examination, which was subsequently compared to ultrasound findings. Biomarker analysis and a patient interview were also carried out. Results were then correlated with the final diagnosis made by a rheumatologist.

Results

A total of 9 variables were identified as having high specificity and good predictive value: loss of appetite, swelling of metacarpophalangeal joint 2 or 5, swelling of proximal inter-phalangeal joint 2 or 3, wrist swelling, wrist tenderness, a positive test for rheumatoid factor, and a positive test for anti-citrullinated protein antibodies.

Conclusion

Nine variables should be the basis of early referral criteria. It should aid PCPs in making appropriate early referrals of patients with suspected inflammatory arthritis, accelerating diagnosis and initiation of treatment.

Lymphatic imaging to assess rheumatoid flare: mechanistic insights and biomarker potential

Proliferation of draining lymphatic vessels coupled with dynamic changes in lymph node volume and flow are characteristic features in rheumatoid arthritis (RA). Furthermore, impaired lymph egress from inflamed synovium is associated with joint flare in murine models of inflammatory-erosive arthritis. Unfortunately, advances towards a greater understanding of lymphatic changes in RA pathogenesis have been slow due to the absence of outcome measures to quantify lymphatic function in vivo. While lymphoscintigraphy is the current standard to assess lymphedema and sentinel lymph nodes in cancer patients, its sensitivity and specificity are inadequate to study lymphatics in RA. The emergence of high-resolution MRI, power Doppler ultrasound, and near-infrared imaging that permits real-time quantification of lymphatic function in animal models has been a major advance, and these techniques have produced a new paradigm of altered lymphatic function that underlies both acute arthritic flare and chronic inflammation. In acute flare, lymphatic drainage increases several fold, whereas no lymphatic contractions are detected in lymph vessels draining chronic arthritic joints. Moreover, these outcomes are now being adapted to study lymphatics in RA towards the development of novel biomarkers of arthritic flare and the discovery of new therapeutic targets. In particular, interventions that directly increase lymphatic egress from diseased joints by opening collateral lymphatic vessels, and that restore lymphatic vessel contractions, provide novel therapeutic approaches with potential for minimal toxicity and immunosuppression. To summarize the origins of this field, recent advances, and future directions, we herein review: current knowledge of lymphatics in RA based on classic literature; new in-vivo imaging modalities that have elucidated how lymphatics modulate acute versus chronic joint inflammation in murine models; and how these preclinical outcome measures are being translated to study lymphatic function in RA inflammation and how effective RA therapies alter lymphatic flow and lymph nodes draining flaring joints.

Trial registration: ClinicalTrials.gov NCT02680067. Registered 7 December 2015; ClinicalTrials.gov NCT01098201. Registered 30 March 2010; and ClinicalTrials.gov NCT01083563. Registered 8 March 2010.

Utility of ultrasonography in guiding modification of disease modifying anti-rheumatic drugs and steroid therapy for inflammatory arthritis in routine clinical practice

OBJECTIVE

To determine the utility of ultrasonography in guiding modification of disease-modifying anti-rheumatic drug (DMARD) and steroid therapy for inflammatory arthritis (IA) in routine clinical practice.

METHODS

In this retrospective study, we analyzed DMARD and steroid use in IA patients referred to a rheumatologist-led ultrasound clinic. Power Doppler (PD) vascularity and greyscale (GS) synovial hypertrophy joint findings were categorized as positive/negative for each patient. The erythrocyte sedimentation rate (ESR) was used as a measure of disease activity.

RESULTS

We assessed single visit data for 46 adult IA patients: 67.4% (n = 31) rheumatoid arthritis (RA), 15.2% (n = 7) psoriatic arthritis, 10.9% (n = 5) spondyloarthritis, and 6.5% (n = 3) undifferentiated IA. The mean ESR was 28.8 mm/h. Thirty-seven patients with both GS and PD ultrasound results were subsequently analyzed. All patients (n = 10) escalated and/or initiated on DMARD and 9/10 patients escalated or initiated on steroids were PD and GS positive. Six of seven patients with dose reduction and/or cessation of DMARDs and five of seven patients with dose reduction or cessation of steroids were PD negative. Of six patients who were GS positive and PD negative, three had dose reduction and/or cessation of DMARDs, while four had dose reduction of steroids; none of the six patients had DMARD/steroid escalation.

CONCLUSION

By clarifying joint inflammation in an IA cohort with overall low ESR, ultrasonography of physician-selected joints can improve clinical assessment, resulting in treatment modification. Positive PD findings were particularly influential, while the clinical significance of GS positivity alone requires further investigation.

Magnetic resonance and ultrasound contrast imaging of polymer-shelled microbubbles loaded with iron oxide nanoparticles

Dual-mode contrast agents (CAs) have great potential for improving diagnostics. However, the effectiveness of CAs is strictly related to both the solution adopted to merge the two agents into a single probe unit, and the ratio between the two agents. In this study, two dual-mode CAs for simultaneous magnetic resonance imaging (MRI) and ultrasound imaging (UI) were assessed. For this purpose, different densities of superparamagnetic iron oxide nanoparticles (SPIONs) were anchored to the external surface of polymer-shelled microbubbles (MBs) or were physically entrapped into the shell. In vitro static and dynamic experiments were carried out with a limited concentration of modified MBs (10⁶ bubbles ml^-1) by avoiding destruction during UI (performed at a peak pressure lower than 320 kPa) and by using a low-field MRI system (with a magnetic flux density equal to 0.25 T). Under these conditions, different imaging techniques, set-up parameters and SPION densities were used to achieve satisfactory detection of the CAs by using both UI and MRI. However, when the SPION density was increased, the MRI contrast improved, whereas the UI contrast worsened due to the reduced elasticity of the MB shell. For both UI and MRI, MBs with externally anchored SPIONs provided better performance than MBs with SPIONs entrapped into the shell. In particular, a SPION density of 29% with respect to the mass of the MBs was successfully tested.

Magnetic resonance and ultrasound contrast imaging of polymer-shelled microbubbles loaded with iron oxide nanoparticles

Dual-mode contrast agents (CAs) have great potential for improving diagnostics. However, the effectiveness of CAs is strictly related to both the solution adopted to merge the two agents into a single probe unit, and the ratio between the two agents. In this study, two dual-mode CAs for simultaneous magnetic resonance imaging (MRI) and ultrasound imaging (UI) were assessed. For this purpose, different densities of superparamagnetic iron oxide nanoparticles (SPIONs) were anchored to the external surface of polymer-shelled microbubbles (MBs) or were physically entrapped into the shell. In vitro static and dynamic experiments were carried out with a limited concentration of modified MBs (10⁶ bubbles ml^-1) by avoiding destruction during UI (performed at a peak pressure lower than 320 kPa) and by using a low-field MRI system (with a magnetic flux density equal to 0.25 T). Under these conditions, different imaging techniques, set-up parameters and SPION densities were used to achieve satisfactory detection of the CAs by using both UI and MRI. However, when the SPION density was increased, the MRI contrast improved, whereas the UI contrast worsened due to the reduced elasticity of the MB shell. For both UI and MRI, MBs with externally anchored SPIONs provided better performance than MBs with SPIONs entrapped into the shell. In particular, a SPION density of 29% with respect to the mass of the MBs was successfully tested.

Nanosized Ultrasound Enhanced-Contrast Agent for in Vivo Tumor Imaging via Intravenous Injection

To enhance the detection limit of ultrasound (US) imaging, ultrasound enhanced-contrast agents (UECAs) that can go preferentially to the target tissue such as a tumor and amplify the US signal have been developed. However, nanosized UECAs among various UECAs developed are very limited to clearly demonstrate proper ability for selective tumor detection by US imaging upon their intravenous injection. In this study, we prepared CaCO3 nanoparticles that were formed inside a flexible and biocompatible pluronic-based nanocarrier. This nanosized UECA was stable in serum-containing media and generated CO2, more preferentially at low pH; thus, it could be detected by US imaging. After intravenous injection into tumor-bearing mice, this nanosized UECA showed a significant US contrast enhancement at the tumor site in 1 h, in contrast to no change in the liver, followed by a rapid clearance from the body in 24 h. Therefore, the present nanosized UECA could be applied as an effective diagnostic modality for in vivo tumor imaging by ultrasonography.

Gray-scale and color duplex Doppler ultrasound of hand joints in the evaluation of disease activity and treatment in rheumatoid arthritis

AIM

To evaluate the role of gray-scale and color duplex-Doppler ultrasound (CDUS) in diagnosis of changes of hand joints and assessment of treatment efficacy in patients with rheumatoid arthritis (RA) by comparing qualitative and quantitative US parameters with clinical and laboratory indicators of disease activity.

METHODS

Ulnocarpal (UC), metacarpophalangeal (MCP), and proximal interphalangeal (PIP) joints in 30 patients with RA were examined by gray-scale and CDUS before and after six months of treatment. Morphologic and quantitative Doppler findings (synovial thickness, effusion quantity, vascularization degree, resistance index, velocities) were compared with clinical indicators of disease progression: disease activity score (DAS 28), Health Assessment Questionnaire (HAQ), rheumatoid factor (RF), erythrocyte sedimentation rate (ESR), and C reactive protein (CRP).

RESULTS

Clinical indicators changed significantly after treatment: ESR from 38.1±22.4 mm/h to 27.8±20.9 mm/h (P=0.013), DAS 28 from 5.47±1.56 to 3.87±1.65 (P<0.001), and HAQ from 1.26±0.66 to 0.92±0.74 (P=0.030), indicating therapeutic effectiveness. In all MCP and UC joints we observed a significant change in at least one US parameter, in 6 out of 12 joints we observed a significant change in ≥2 parameters, and in 2 UC joints we observed significant changes in ≥3 parameters. The new finding was that the cut-off values of resistance index of 0.40 at baseline and of 0.55 after the treatment indicated the presence of active disease and the efficacy of treatment, respectively; also it was noticed that PIP joints can be omitted from examination protocol.

CONCLUSION

Gray scale and CDUS are useful in diagnosis of changes in UC and MCP joints of patients with RA and in monitoring the treatment efficacy.

The Role of Power Doppler Ultrasonography as Disease Activity Marker in Rheumatoid Arthritis

Structural damage in rheumatoid arthritis (RA) occurs early if inflammation is not treated promptly. Treatment targeted to reduce inflammation, in particular, that of synovial inflammation in the joints (synovitis), has been recommended as standard treat-to-target recommendations by rheumatologists. The goal is to achieve disease remission (i.e., no disease activity). Several accepted remission criteria have not always equated to the complete absence of true inflammation. Over the last decade, musculoskeletal ultrasonography has been demonstrated to detect subclinical synovitis not appreciated by routine clinical or laboratory assessments, with the Power Doppler modality allowing clinicians to more readily appreciate true inflammation. Thus, targeting therapy to Power Doppler activity may provide superior outcomes compared with treating to clinical targets alone, making it an attractive marker of disease activity in RA. However, more validation on its true benefits such as its benefits to patients in regard to patient related outcomes and issues with standardized training in acquisition and interpretation of power Doppler findings are required.

Validation of power Doppler versus contrast-enhanced magnetic resonance imaging quantification of joint inflammation in murine inflammatory arthritis

Contrast-enhancement magnetic resonance imaging (CE-MRI) of synovial volume is the radiographic gold standard to quantify joint inflammation; however, cost limits its use. Therefore, we examined if power Doppler-ultrasound (PD-US) outcomes of synovitis in tumor necrosis factor transgenic (TNF-Tg) mice correlate with CE-MRI. TNF-Tg mice underwent PD-US of their knees to measure the joint space volume (JSV) and power Doppler volume (PDV), and the results were correlated with synovial volume determined by CE-MRI. Immunohistochemistry for CD31 was performed to corroborate the PD signal. Synovial volume strongly correlated with both JSV and PDV (p < 0.01). CD31(+) blood vessels were observed in inflamed synovium proximal to the joint surface, which corresponded to areas of intense PD signals. JSV and PDV are valid measures of joint inflammation that correlate with synovial volume determined by CE-MRI and are associated with vascularity. Given the emergence of PD-US as a nonquantitative outcome of joint inflammation, we find JSV and PDV to be feasible and highly cost-effective for longitudinal studies in animal models. Furthermore, given the increasing use of PD-US in standard clinical practice, JSV and PDV could be translated to better quantify joint flare and response to therapy in patients with rheumatoid arthritis (RA).

Cartilage Thickness of the Knee Joint in Juvenile Idiopathic Arthritis: Comparative Assessment by Ultrasonography and Magnetic Resonance Imaging

Objective.

The functional disability experienced in juvenile idiopathic arthritis (JIA) is primarily caused by joint effusion, synovial membrane hypertrophy, and periarticular soft tissue edema, leading to the degeneration of the osteocartilaginous structures because of the inflammatory process in the synovium. The ability to visualize the inflammatory changes and hence the ensuing osteocartilaginous degeneration is, therefore, of great importance in pediatric rheumatology. Ultrasonography (US) has been validated as a tool for measuring cartilage thickness in healthy children and, previously, we have found good agreement with the measures obtained by magnetic resonance imaging (MRI). Our aim is to validate and compare US with MRI measurements of distal femoral cartilage thickness in the knee joint at the medial condyle, lateral condyle, and intercondylar spots in children with JIA, and to locate the best spot for imaging comparisons.

Methods.

One knee from each of 23 children with oligoarticular JIA were investigated by both MRI and US. Outcome measures of imaging procedures were distal femoral cartilage thickness.

Results.

We found a high level of agreement between MRI and US measurements of mean cartilage thickness, and Rho values between modalities were high (between 0.70 and 0.86, p < 0.05 for all). We found a thinner cartilage thickness at the medial condyle in comparison to the other investigated points. Evaluation of anatomical landmarks for optimal measurement of cartilage thickness was found to be the intercondylar spot, which was easier to locate in addition to a smaller variance around the mean for that anatomical measuring point.

Conclusion.

US measurements of distal femoral cartilage thickness are highly correlated to MRI measurements. The intercondylar notch of the distal femoral cartilage may be the best anatomical point for cartilage thickness measurements of the knee. US is a reliant and nonexpensive, non-invasive modality for visualization of childhood femoral cartilage.

Insights from populations at risk for the future development of classified rheumatoid arthritis

Rheumatoid arthritis (RA) develops through a series of stages. In the seropositive subset of classified RA patients, a preclinical stage is present for years before the onset of clinically apparent disease. Relevant preclinical biomarkers include autoantibodies, alterations of lymphoid populations, elevated cytokines/chemokines, genetic/genomic factors, imaging studies, clinical findings, dietary and environmental biomarkers, cardiovascular disease risk assessment, microbiome analyses, and metabolomic changes. Identifying the population of asymptomatic subjects at sufficiently high risk for disease to be informative and representative of "preclinical patients" is a challenge. This article reviews the results of analyses that have been undertaken in these "at-risk" subjects.

Power Doppler ultrasound phenotyping of expanding versus collapsed popliteal lymph nodes in murine inflammatory arthritis

Rheumatoid arthritis is a chronic inflammatory disease manifested by episodic flares in affected joints that are challenging to predict and treat. Longitudinal contrast enhanced-MRI (CE-MRI) of inflammatory arthritis in tumor necrosis factor-transgenic (TNF-Tg) mice has demonstrated that popliteal lymph nodes (PLN) increase in volume and contrast enhancement during the pre-arthritic “expanding” phase of the disease, and then suddenly “collapse” during knee flare. Given the potential of this biomarker of arthritic flare, we aimed to develop a more cost-effective means of phenotyping PLN using ultrasound (US) imaging. Initially we attempted to recapitulate CE-MRI of PLN with subcutaneous footpad injection of US microbubbles (DEFINITY®). While this approach allowed for phenotyping via quantification of lymphatic sinuses in PLN, which showed a dramatic decrease in collapsed PLN versus expanding or wild-type (WT) PLN, electron microscopy demonstrated that DEFINITY® injection also resulted in destruction of the lymphatic vessels afferent to the PLN. In contrast, Power Doppler (PD) US is innocuous to and efficiently quantifies blood flow within PLN of WT and TNF-Tg mice. PD-US demonstrated that expanding PLN have a significantly higher normalized PD volume (NPDV) versus collapsed PLN (0.553±0.007 vs. 0.008±0.003; p<0.05). Moreover, we define the upper (>0.030) and lower (<0.016) quartile NPDVs in this cohort of mice, which serve as conservative thresholds to phenotype PLN as expanding and collapsed, respectively. Interestingly, of the 12 PLN phenotyped by the two methods, there was disagreement in 4 cases in which they were determined to be expanding by CE-MRI and collapsed by PD-US. Since the adjacent knee had evidence of synovitis in all 4 cases, we concluded that the PD-US phenotyping was correct, and that this approach is currently the safest and most cost-effective in vivo approach to phenotype murine PLN as a biomarker of arthritic flare.