Ultrasound as an Outcome Measure in Gout. A Validation Process by the OMERACT Ultrasound Working Group

Prevalence of crystal deposits in asymptomatic hyperuricemia according to different scanning definitions: A comparative study

BACKGROUND/AIM

The appropriate sonographic protocol for assessing urate crystal deposits in asymptomatic hyperuricemia (AH) is undefined, as well as how the choice would impact on deposit rates and accompanying sonographic, clinical and laboratory features.

METHODS

Patients with AH (serum urate ≥7 mg/dL) underwent musculoskeletal ultrasound of 10 locations for OMERACT elementary gout lesions (double contour [DC] signs, tophi, aggregates). Different definitions for AH with deposits were applied, varying according to deposits (any deposits; only DC and/or tophi); gradation (any grade; only grade 2-3 deposits), location (10 locations; 4-joint scheme including knees and 1MTPs; >1 location with deposits), or pre-defined definitions (DC sign in femoral condyles/1MTP and/or tophi in 1MTP). We evaluated crystal deposits rates and compared between other sonographic features, clinical and laboratory variables.

RESULTS

Seventy-seven participants with AH showed a median 1 location (IQR 0-2) with tophi, 1 (IQR 1-2) with aggregates, and 0 locations (IQR 0-1) with DC sign. The deposition rate ranged from 23.4% (in >1 location with grade 2-3 DC or tophi) to 87.0% (in any deposit in all 10 locations). Accompanying inflammation - assessed by a positive power-Doppler (PD) signal - and erosions were found in 19.5% and 28.4% of participants, respectively. Positive PD signal was better discriminated by criteria requiring grade 2-3 or >1 location with lesions. Erosions and the different clinical and laboratory variables were similar among protocols.

CONCLUSION

Rates of sonographic deposition in AH varied dramatically among studied protocols, while some could discriminate accompanying inflammation, all highlighting the need for a validated, consensus-based definition.

Concordance of Ultrasound and Dual-Energy CT in Diagnosing Gouty Arthritis in the Knee Joint: A Retrospective Observational Study

RATIONALE AND OBJECTIVES

To assess the consistency between ultrasound and dual-energy computed tomography (DECT) for the diagnosis of gout in the knee joint.

MATERIALS AND METHODS

The ultrasound and DECT images of 176 knee joints from 167 patients diagnosed with gout at the Gout Specialty Clinic of Qingdao University Affiliated Hospital from February 2022 to December 2023 were retrospectively analyzed. The knee joint was segmented into five anatomical regions: intra-articular, anterior, posterior, medial, and lateral. The location of monosodium urate (MSU) crystal deposition was recorded. Tophi were classified as hypoechogenic, isoechogenic, hyperechogenic, or strongly echogenic. The Kappa test was used to assess the consistency between the two examination methods in different regions of the knee joint. The McNemar chi-square test was utilized to conduct a differential analysis between the DECT and ultrasound results. The chi-square test was used to assess differences in the rate of tophi detection with different echogenicities by DECT. Pearson's correlation coefficient was used to assess the correlation between MSU crystal deposition volume and clinically relevant indicators.

RESULTS

Double contour (61.4%) was the most common intra-articular ultrasound sign. In the extra-articular region, MSU crystals were commonly deposited in and around the popliteal groove region (ultrasound: 52.3%; DECT: 60.0%). Corresponding MSU deposits on DECT were found in 7 of 54 joints with aggregates detected on ultrasound, and in 15 of 108 joints with DC. Tophi with hyperechogenicity or strong echogenicity were more likely to be detected on DECT than those with hypoechoic or isoechoic features (84.3% and 90.9% vs. 55.1% and 27.8%, respectively). For the assessment of MSU deposits, ultrasound showed an overall higher positive rate than DECT (81.1% vs. 72.2%), with poor consistency between the two examinations (κ = 0.177). In distinct anatomical regions, ultrasound and DECT showed high consistency in the medial (κ = 0.651) and lateral (κ = 0.705) views, with no significant difference. The intra-articular (κ = 0.316) and anterior (κ = 0.346) regions exhibited only fair consistency, with statistically significant diagnostic differences. When exclusively assessing cases with tophi, ultrasound and DECT demonstrated similar consistency in the medial, lateral and anterior views (κ = 0.633, 0.712, and 0.400, respectively), with statistically significant differences. In the intra-articular region, the consistency was reduced (κ = 0.237), and the differences were statistically significant.

CONCLUSION

Ultrasound and DECT are effective methods to detect MSU deposition in gout of the knee. However, the consistency between the two techniques varies in different anatomical locations. Clinical assessment should be tailored based on the specific anatomical position. DECT is advantageous for the evaluation of intra-articular MSU deposits, while ultrasound is more sensitive for the early detection of scattered MSU deposits.

Associations of Changes in Knee Hyaline Cartilage Composition Measured With Dual-Energy Computed Tomography in Gout, Aging and Osteoarthritis

OBJECTIVE

To characterize dual-energy computed tomography (DECT) changes depicting hyaline cartilage changes in gout patients with and without osteoarthritis (OA) and in comparators without gout.

DESIGN

Patients with suspected crystal-associated arthropathy were enrolled and underwent bilateral DECT scans of the knees. Standardized regions of interest were defined in the femorotibial hyaline cartilage. Five DECT parameters were obtained: CT numbers in Hounsfield units (HU) at 80 and 140 kV, the electron density (Rho), the effective atomic number (Zeff), and the dual-energy index (DEI). Zones were compared between patients with gout, with and without knee OA, and between patients with gout and comparators without gout, after adjustment for confounders.

RESULTS

A total of 113 patients with gout (mean age 63.5 ± 14.3 years) and 15 comparators without gout (mean age 75.8 ± 11.5 years) were included, n = 65 (51%) had knee OA, and 466 zones of hyaline cartilage were analyzed. Older age was associated with lower attenuations at 80 kV (P < 0.01) and 140 kV (P < 0.01), and with Rho (P < 0.01). OA was characterized by lower attenuation at 140 kV (P = 0.03), but the lower Rho was nonsignificant after adjustment for confounders. In gout, hyaline cartilage exhibited lower Rho values (adjusted P = 0.04). Multivariable coefficients of association with Rho were -0.21 [-0.38;-0.04] (P = 0.014) for age, -4.15 [-9.0;0.7] (P = 0.093) for OA and 0.73 [-0.1;1.56] (P = 0.085) for monosodium urate volume.

CONCLUSION

Gout was associated with DECT-detected changes in cartilage composition, similar to those observed in older patients, with some similarities and some differences to those seen in OA. These results suggest the possibility of potential DECT biomarkers of OA.

The value of musculoskeletal ultrasound in predicting gout flares in index joints: A prospective cohort study of people with gout starting urate-lowering therapy

OBJECTIVES

To evaluate whether ultrasound findings of monosodium urate (MSU) crystal deposition predict frequent gout flares in index joints over 12 months.

METHODS

This single-center study enrolled people with at least one gout flare involving the MTP1, ankle or knee joint. The most painful or most frequently joint was identified as index joint for analysis. All participants were started on urate-lowering therapy and had an ultrasound scan of the index joints at the baseline visit. OMERACT scores (for tophus, double contour sign and aggregates) were used to analyze whether ultrasound scores predicted frequent (≥2) gout flares in the index joint over 12 months.

RESULTS

Frequent flares were significantly higher in those with ultrasound findings in all index joints (MTP1: tophus: 85.0% vs 46.0%, P < 0.001, aggregates: 78.8% vs 59.0%, P < 0.01; ankle: tophus: 54.6% vs 20.8%, P < 0.001; aggregates: 60.0% vs 35.9%, P < 0.05; knee: tophus: 68.4% vs 28.6%, P < 0.05). For the MTP1, for each 1-point increase in tophus score, the odds of frequent gout flares increased by 5.19 [(95%CI: 1.26-21.41), 7.91 [(95%CI: 2.23-28.14), and 13.79 [(95%CI: 3.79-50.20)] fold respectively. For the ankle, a tophus score of 3 markedly improved the prediction of the frequent flares [OR= 9.24 (95%CI=2.85-29.91)]. Semi-quantitative sum scores were associated with frequent flares with an OR (95%CI) of 13.66 (3.44-54.18), P < 0.001 at the MTP1, 7.05 (1.98-25.12), P < 0.001 at the ankle.

CONCLUSION

Ultrasound features of MSU crystal deposition at the MTP1 and knee predict subsequent risk of frequent gout flares in the same joints following initiation of urate-lowering therapy, with the highest risk in those with high tophus scores.

Ultrasound Features in Gout: An Overview

The accurate diagnosis of gout frequently constitutes a challenge in clinical practice, as it bears a close resemblance to other rheumatologic conditions. An undelayed diagnosis and an early therapeutic intervention using uric acid lowering therapy (ULT) is of the utmost importance for preventing bone destruction, the main point of managing gout patients. Advanced and less invasive imaging techniques are employed to diagnose the pathology and ultrasonography (US) stands out as a non-invasive, widely accessible and easily reproducible method with high patient acceptability, enabling the evaluation of the full clinical spectrum in gout. The 2023 EULAR recommendations for imaging in diagnosis and management of crystal-induced arthropathies in clinical practice state that US is a fundamental imagistic modality. The guidelines underline its effectiveness in detecting crystal deposition, particularly for identifying tophi and the double contour sign (DCS). Its utility also arises in the early stages, consequent to synovitis detection. US measures of monosodium urate (MSU) deposits are valuable indicators, sensitive to change consequent to even short-term administration of ULT treatment, and can be feasibly used both in current daily practice and clinical trials. This paper aimed to provide an overview of the main US features observed in gout patients with reference to standardized imaging guidelines, as well as the clinical applicability both for diagnosis accuracy and treatment follow-up. Our research focused on summarizing the current knowledge on the topic, highlighting key data that emphasize gout as one of the few rheumatological conditions where US is recognized as a fundamental diagnostic and monitoring tool, as reflected in the most recent classification criteria.

Describing calcium pyrophosphate deposition: undoing the tower of Babel!

PURPOSE OF REVIEW

In 1977, McCarty astutely observed, 'The variety of names suggested for the condition associated with deposits of calcium pyrophosphate dihydrate crystals is exceeded only by the variations of its clinical presentation'. Fast forward to 2024, a standardized nomenclature for calcium pyrophosphate deposition (CPPD) is still lacking. This review aims to delineate the challenges in characterizing CPPD through nomenclature and imaging.

RECENT FINDINGS

Despite the effort of nomenclature standardization in 2011 by the EULAR, confusion persists in the literature and clinical practice, with pseudo-forms and obscure abbreviations. The Gout, Hyperuricemia and Crystal-Associated Disease Network (G-CAN) has launched a project to redefine CPPD nomenclature and formulate a user-friendly language for effective communication with patients and other stakeholders. Additionally, recent advancements in imaging, have shed light on various aspects of the disorder.

SUMMARY

Almost 60 years from the first description of a clinical manifestation related to calcium pyrophosphate crystals, a common language describing the disorder is still lacking. A redefined CPPD nomenclature, together with lay-friendly terminology, would significantly contribute to the uniformity of CPPD research, enhance public understanding and awareness and improve doctor-patient communication and therefore disease outcomes. Imaging can provide deep insights into CPPD elements, promoting comprehension of this disorder.

Unsupervised cluster analysis of clinical and ultrasound features reveals unique gout subtypes: Results from the Egyptian College of Rheumatology (ECR)

BACKGROUND

Gout comprises a heterogeneous group of disorders; however, comorbidities have been the focus of most efforts to classify disease subgroups.

OBJECTIVES

We applied cluster analysis using musculoskeletal ultrasound (MSUS) combined with clinical and laboratory findings in patients with gout to identify disease phenotypes, and differences across clusters were investigated.

PATIENTS AND METHODS

Patients with gout who complied with the ACR/EULAR classification criteria were enrolled in the Egyptian College of Rheumatology (ECR)-MSUS Study Group, a multicenter study. Selected variables included demographic, clinical, and laboratory findings. MSUS scans assessed the bilateral knee and first metatarsophalangeal joints. We performed a K-mean cluster analysis and compared the features of each cluster.

RESULTS

425 patients, 267 (62.8 %) males, mean age 54.2 ± 10.3 years were included. Three distinct clusters were identified. Cluster 1 (n = 138, 32.5 %) has the lowest burden of the disease and a lower frequency of MSUS characteristics than the other clusters. Cluster 2 (n = 140, 32.9 %) was mostly women, with a low rate of urate-lowering treatment (ULT). Cluster 3 (n = 147, 34.6 %) has the highest disease burden and the greatest proportion of comorbidities. Significant MSUS variations were found between clusters 2 and 3: joint effusion (p < 0.0001; highest: cluster 3), power Doppler signal (p < 0.0001; highest: clusters 2), and aggregates of crystal deposition (p < 0.0001; highest: cluster 3).

CONCLUSION

Cluster analysis using MSUS findings identified three gout subgroups. People with more MSUS features were more likely to receive ULT. Treatment should be tailored according to the cluster and MSUS features.

Prediction of renal and cardiometabolic outcomes in gout during urate-lowering therapy by sonography

OBJECTIVES

To assess whether the extent of monosodium urate (MSU) crystal deposition estimated by ultrasound could predict renal and cardiometabolic events during urate-lowering therapy (ULT).

METHODS

A prospective study on gout patients from two referral centers initiating ULT who underwent baseline ultrasound and were followed for 1 year. Ultrasound scans assessed six joints for double-contour (DC) signs and tophi. A five-point change (mL/min/1.73 m2 ) in the glomerular filtration rate at month 12 (M12) was considered significant. Outcomes of interest were renal function degraded versus improved and a composite cardiometabolic outcome (new hypertension, diabetes, atherosclerotic disease, and cardiovascular death). Homogeneity analyses and Cox regression models were performed.

RESULTS

One hundred sixty patients were recruited. At baseline, 81.1% of patients (n = 129) showed sonographic tophi with a mean number of 1.4 joints (±1.3) with a DC sign. At M12, 18 patients (11.3%) were lost to follow-up. The serum urate (SU) target (<6.0 mg/dL) was reached in 86 patients (69.9%). Regarding renal function, 15.9% of patients showed improvement, while in 31.0% it degraded. Fourteen new cardiometabolic events occurred in 12 patients. Neither the DC sign nor tophi showed any significant impact on the outcomes of interest. Baseline SU level was higher in those with renal improvement but not with renal decline, while achieving the SU target protected against new cardiometabolic events (HR = 0.2; 95% CI: 0.05-0.81).

CONCLUSIONS

Sonographic MSU crystal burden was unhelpful in predicting renal and cardiometabolic events during the first year of ULT. Reaching the SU target prevented cardiometabolic events, while its benefit in preserving/improving renal function is unclear.

The EFSUMB Guidelines and Recommendations for Musculoskeletal Ultrasound - Part II: Joint Pathologies, Pediatric Applications, and Guided Procedures

The second part of the Guidelines and Recommendations for Musculoskeletal Ultrasound (MSUS), produced under the auspices of EFSUMB, following the same methodology as for Part 1, provides information and recommendations on the use of this imaging modality for joint pathology, pediatric applications, and musculoskeletal ultrasound-guided procedures. Clinical application, practical points, limitations, and artifacts are described and discussed for every joint or procedure. The document is intended to guide clinical users in their daily practice.

Sonographic Tophi and Inflammation Are Associated With Carotid Atheroma Plaques in Gout

Objective: Gout and cardiovascular disease are closely related, but the mechanism connecting them remains unknown. This study aims to explore whether urate crystal deposits and inflammation (assessed by ultrasound) are associated with carotid atherosclerosis.

Methods: We included consecutive patients with crystal-proven gout newly presenting to a tertiary rheumatology unit. Patients under urate-lowering treatment were excluded. Ultrasound assessment was performed during intercritical periods. Musculoskeletal scans evaluated six joints and four tendons for urate crystal deposits (double contour, aggregates, and tophi), and power Doppler (PD) signal (graded 0–3) as a marker of local inflammation. The sum of locations showing deposits or a positive PD signal (≥1) was registered. Carotids were scanned for increased intima-media thickness (IMT) and atheroma plaques, according to the Mannheim consensus. Associations were analyzed using logistic regression.

Results: The study included 103 patients showing sonographic crystal deposits at the examined locations (mean sum 9.9, minimum 2); tophi were the most frequent. Two-thirds of participants presented a positive PD signal (30.1% grade 2–3). In the carotid scans, 59.2% of participants showed atheroma plaques, and 33.0% increased IMT. Tophi (odds ratio [OR] 1.24; 95% confidence interval [CI] 1.03–1.50) and a positive PD signal (OR 1.67; 95% CI 1.09–2.56) were significantly associated with atheroma plaques, while an increased IMT showed no sonographic association.

Conclusion: Sonographic crystal deposits and subclinical inflammation were consistently observed in patients with intercritical gout. Tophi and a positive PD signal were linked to carotid atherosclerosis. Our findings may contribute to understanding the complex relationship between gout and atherosclerosis.

Diagnostic Performance of Dual-energy CT Versus Ultrasonography in Gout: A Meta-analysis

OBJECTIVE

Dual-energy computed tomography (DECT), along with ultrasound (US), has been increasingly utilized for the diagnosis of gout because of its noninvasive advantages. However, the superiority of DECT over US remains controversial. This meta-analysis was performed to investigate whether DECT is superior to US in the diagnosis of gout.

METHODS

A comprehensive search of PubMed, EMBASE, Cochrane, and Web of Science databases was conducted for potentially eligible articles. Studies that evaluated the utility of DECT or US for gout diagnosis were qualified. Two distinctive ultrasonographic features of gout, namely, the double contour sign and the presence of tophus, were also assessed. The methodological quality of the included studies was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 criteria. Besides, the subgroup analyses of early disease duration (≤ 2 years) was also performed.

RESULTS

Twenty-eight studies were included in the meta-analysis. The pooled sensitivity and specificity of DECT were 0.89 (0.80-0.94) and 0.91 (0.88-0.94), respectively. The pooled sensitivity and specificity of US were 0.70 (0.58-0.79) and 0.95 (0.87-0.98), respectively, for double contour sign; 0.57 (0.38-0.74) and 0.99 (0.88-1.00), respectively, for tophus; and 0.84 (0.73-0.91) and 0.84 (0.78-0.89), respectively, for overall consideration of US signs. At the early disease duration (≤ 2 years), the pooled sensitivity and specificity were 0.75 (0.60-0.86) and 0.85 (0.75-0.91), respectively, for DECT; 0.93 (0.72-0.99) and 0.80 (0.71-0.86), respectively, for overall consideration of US signs.

CONCLUSION

DECT and US showed promising accuracy for gout diagnosis. DECT has higher sensitivity, specificity, and AUC than overall consideration of US signs and thus has a better diagnostic ability in diagnosing gout. Moreover, the diagnostic sensitivity of DECT is lower than that of overall consideration of US signs at less than 2 years' disease duration.

Update of the current role of ultrasound in asymptomatic hyperuricemia. A systematic literature review

Ultrasound (US) is a recognized imaging modality for the assessment of gout. Recently it is being explored for its potential role in the evaluation of subjects with asymptomatic hyperuricemia (AH). Preliminary reports demonstrated the presence of monosodium urate (MSU)-crystal deposits including aggregates, double contour sign and/or tophi in both intra-articular and periarticular tissues of AH individuals. Although these results are exciting, the value and potential application of US in AH remain to be clearly delineated. In this systematic literature review, we aim to summarise the recent publications regarding the role of US in the assessment of AH. We analyzed possible application of US in the daily clinical practice and its future clinical and research potential in the evaluation of AH individuals.

Diagnostic value of different imaging features for patients with suspected gout: A network meta-analysis

OBJECTIVE

Microscopic identification of monosodium urate (MSU) crystals is the gold standard for gout diagnosis. However, joint aspiration is not always practical, and imaging is increasingly used in clinical practice. This study aimed to assess the diagnostic accuracy of imaging features for gout compared with microscopy, using network meta-analysis methodology.

METHODS

MEDLINE, EMBASE, PubMed and Cochrane databases were searched for studies reporting on the use of imaging modalities to diagnose gout in patients with an unclear diagnosis or suspected gout, which was later confirmed by microscopy. A combination of direct and indirect comparisons were performed by network meta-analysis to evaluate the combined odds ratios for sensitivity, specificity, and accuracy. To assist interpretation, the surface under the cumulative ranking curve (SUCRA) scores were calculated to provide a ranking of the imaging features.

RESULTS

Fifteen eligible studies were included. Compared to the gold standard microscopic identification of MSU crystals, dual energy computed tomography (DECT) MSU crystal deposition and ultrasound double contour had greater sensitivity than ultrasound tophus. DECT, ultrasound double contour sign and ultrasound tophus all had greater specificity than ultrasound aggregates. The SUCRA scores ranked DECT as highest for overall accuracy, followed by ultrasound double contour, aggregates, and tophus, while ultrasound snowstorm was ranked the lowest. However, there were no significant differences in the odds ratios for overall accuracy between these imaging features.

CONCLUSION

DECT and ultrasound are both useful modalities for the detection of imaging features of MSU crystal deposition, and have a similar overall diagnostic accuracy for gout diagnoses.

Quantitative assessment of crystal dissolution in gout during urate-lowering therapy with computer-aided MicroPure imaging: a cohort study

Background

To evaluate whether MicroPure imaging, an ultrasound (US) image-processing technique with computer-aided analysis, can quantitatively detect crystal dissolution during urate-lowering therapy (ULT) in gout.

Methods

This was a prospective study of gout patients requiring ULT. The first metatarsophalangeal joints were examined using US and MicroPure before and after 3 months of ULT. Elementary lesions of gout, including the double contour sign (DCS), aggregates, tophi, erosion, and other US features were recorded at baseline and 3 months. MicroPure imaging features were automatically calculated by a self-developed software. Patients were divided into goal-achieved and goal-not-achieved groups according to their urate levels at 3 months. The US and MicroPure imaging features of the two groups were analyzed at baseline and 3 months.

Results

A total of 55 consecutive patients were enrolled (25: goal-achieved group; 30: goal-not-achieved group). US findings demonstrated that the power Doppler signal grade decreased at 3 months, regardless of the group (both P<0.05). From baseline to 3 months, tophi size and the DCS reduced in the goal-achieved group (both P<0.05), while the US aggregate features showed no difference (P=0.250). However, on the MicroPure imaging, the number and density of aggregates at 3 months decreased in the goal-achieved group (both P<0.05). There were no significant changes at 3 months in any of the MicroPure imaging features in the goal-not-achieved group (all P>0.05).

Conclusions

In comparison with B-mode US, computer-aided MicroPure imaging can sensitively and quantitatively detect aggregate dissolution during effective ULT after only 3 months of treatment.

Consensus-based semi-quantitative ultrasound scoring system for gout lesions: Results of an OMERACT Delphi process and web-reliability exercise

OBJECTIVE

This study aimed to develop (1) a new ultrasound definition for aggregates and (2) a semi-quantitative ultrasound scoring system (0-3) for tophus, double contour and aggregates. Furthermore, the intra- and inter-reader reliabilities of both the re-defined aggregates and the semi-quantitative scoring system were assessed using static image exercises.

METHODS

Thirty-seven rheumatologists were invited. A Delphi process was used for re-defining aggregates and for selecting a semi-quantitative scoring system with >75% agreement obligate for reaching consensus. Subsequently, a web-based exercise on static ultrasound images was conducted in order to assess the reliability of both the re-defined aggregates and the semi-quantitative scoring system.

RESULTS

Twenty rheumatologists contributed to all rounds of the Delphi and image exercises. A consensual re-definition of aggregates was obtained after three Delphi rounds but needed an overarching principle for scoring aggregates in patients. A consensus-based semi-quantitative ultrasound scoring system for gout lesions was developed after two Delphi rounds. The re-definition of aggregates showed good intra- and inter-reader reliability (κ-values 0.71 and 0.61). The reliabilities of the scoring system were good for all lesions with slightly higher intra-reader (κ-values 0.74-0.80) than inter-reader reliabilities (κ-values 0.61-0.67).

CONCLUSION

A re-definition of aggregates was obtained with a good reliability when assessing static images. The first consensus-based semi-quantitative ultrasound scoring system for gout-specific lesions was developed with good inter- and intra-reader reliability for all lesions when tested in static images. The next step is to assess the reliabilities when scoring lesions in patients.

Ultrasound shows rapid reduction of crystal depositions during a treat-to-target approach in gout patients: 12-month results from the NOR-Gout study

OBJECTIVES

As ultrasound is sensitive for detecting crystal depositions in patients with gout, our objectives were to explore the main locations for depositions and the extent of dissolution of depositions during a treat-to-target approach with urate lowering treatment (ULT) in patients with gout.

METHODS

Patients with a recent flare of gout were consecutively included in this single-centre study and managed by a treat-to-target approach with ULT. All patients were assessed at baseline, 3, 6 and 12 months including bilateral ultrasound examinations of joints/tendons/entheses of hands, elbows, knees, ankles and feet. A new semiquantitative scoring system of 0-3 of elementary lesions (double contour (DC), tophi and aggregates) was applied to quantify the amount of depositions during the follow-up.

RESULTS

209 of the patients were evaluated with ultrasound at baseline (mean (SD) age 56.4 (13.8) years and disease duration 7.9 (7.7) years, 95.2% men). The serum urate levels decreased from baseline to 12 months (mean (SD) 500 (77) to 312 (49) µmol/L) (p<0.001)). The first metatarsophalangeal joint was the most frequent location for all the elementary lesions and erosions were associated with higher levels of crystal depositions. From baseline to 12 months, mean sum scores decreased for DC (4.3 to 1.3), tophi (6.5 to 3.8) and aggregates (9.3 to 6.7) (p<0.001 for all), with DC being most sensitive to change.

CONCLUSIONS

The ultrasound scoring system for crystal depositions was sensitive to change and showed that a treat-to-target approach with ULT resulted in significant reductions of all the depositions, most extensively for DC.

Clinics in diagnostic imaging (200). Intra-articular chronic tophaceous gout of the knee

A 39-year-old man presented with acute left knee pain and swelling. There was limitation of movement of the knee joint. His past medical history was significant for gout. Computed radiography showed bony erosions that were not typical of chronic tophaceous gout. Magnetic resonance (MR) imaging showed focal deposits within the knee joint, which demonstrated isointense signal to muscle on T1-weighted sequence and intermediate signal on proton density (PD) and PD fat-saturated sequences. There was extensive, similar signal abnormality in the cruciate ligaments, popliteus tendon and lateral meniscus. These findings were in keeping with an intra-articular manifestation of chronic tophaceous gout. The clinical presentation and imaging features are herein discussed, with an emphasis on MR imaging.

Gout: state of the art after a decade of developments

This review article summarizes the relevant English literature on gout from 2010 through April 2017. It emphasizes that the current epidemiology of gout indicates a rising prevalence worldwide, not only in Western countries but also in Southeast Asia, in close relationship with the obesity and metabolic syndrome epidemics. New pathogenic mechanisms of chronic hyperuricaemia focus on the gut (microbiota, ABCG2 expression) after the kidney. Cardiovascular and renal comorbidities are the key points to consider in terms of management. New imaging tools are available, including US with key features and dual-energy CT rendering it able to reveal deposits of urate crystals. These deposits are now included in new diagnostic and classification criteria. Overall, half of the patients with gout are readily treated with allopurinol, the recommended xanthine oxidase inhibitor (XOI), with prophylaxis for flares with low-dose daily colchicine. The main management issues are related to patient adherence, because gout patients have the lowest rate of medication possession ratio at 1 year, but they also include clinical inertia by physicians, meaning XOI dosage is not titrated according to regular serum uric acid level measurements for targeting serum uric acid levels for uncomplicated (6.0 mg/dl) and complicated gout, or the British Society for Rheumatology recommended target (5.0 mg/dl). Difficult-to-treat gout encompasses polyarticular flares, and mostly patients with comorbidities, renal or heart failure, leading to contraindications or side effects of standard-of-care drugs (colchicine, NSAIDs, oral steroids) for flares; and tophaceous and/or destructive arthropathies, leading to switching between XOIs (febuxostat) or to combining XOI and uricosurics.

Impact of Dual-Energy CT Postprocessing Protocol for the Detection of Gouty Arthritis and Quantification of Tophi in Patients Presenting With Podagra: Comparison With Ultrasound

OBJECTIVE. The objective of our study was to compare ultrasound (US) tophus and monosodium urate (MSU) deposit detection and US tophus size in the metatarsophalangeal (MTP) 1 joint with dual-energy CT (DECT) using two DECT postprocessing protocols in patients presenting with podagra. SUBJECTS AND METHODS. Seventy-five consecutive patients with podagra (66 men and nine women; mean age, 65.6 years; age range, 33-88 years) and 75 control subjects with MTP 1 joint osteoarthritis (49 men and 26 women; mean age, 63.0 years; age range, 35-87 years) prospectively underwent US and DECT between 2016 and 2018 to assess the MTP 1 joint. Two Syngovia postprocessing DECT protocols with different minimum attenuation thresholds of 150 HU (DECT 150 protocol) versus 120 HU (DECT 120 protocol) and the same maximum attenuation threshold (500 HU) and constant kilovoltage setting of tubes A and B at 80 and 140 kVp were evaluated. Interobserver variability of the two DECT protocols was calculated and compared with that of US. RESULTS. The postprocessing DECT 150 protocol was positive for tophus detection in 55 of 75 patients (73.3%) with podagra, whereas the postprocessing DECT 120 protocol detected MSU deposits in all 75 patients (100%). Tophus size assessed using the DECT 120 protocol showed an improved correlation with tophus size detected on US (p < 0.01). Interobserver variability of DECT was improved when using the DECT 120 protocol (p < 0.01). CONCLUSION. The postprocessing DECT 120 protocol enables improved visualization of MSU deposits and provides more accurate information about tophus size that better correlates with tophus size on US compared with the standard postprocessing DECT 150 protocol.

Size matters: observations regarding the sonographic double contour sign in different joint sizes in acute gouty arthritis

OBJECTIVE

In distinguishing urate arthritis (UA) from non-crystal-related arthritides, joint sonography including the detection of the double contour sign (DCS) and hypervascularization using power Doppler ultrasound (PDUS) is an important step in the diagnostic process. But are these sonographic features equally reliable in every accessible joint under real-life conditions?

METHODS

We retrospectively analyzed 362 patients with acute arthritis and evaluated the DCS and the degree of PDUS hypervascularization in patients with gout and in those with arthritis other than urate arthritis (non-UA). We classified all joints into the groups small, medium, and large. Sensitivities, specificities, positive and negative predictive values (PPV/NPV), and a binary regression model were calculated. We also evaluated the influence of serum uric acid levels (SUA) on the presence of a DCS in each joint category.

RESULTS

Sensitivity of the DCS in gout was 72.5% in the entire cohort, 66.0% in large, 78.8% in medium, and 72.3% in small joints. In wrist joints the DCS sensitivity maxed at 83.3%, with a specificity of 81.8%. The lowest rates of DCS sensitivity were found in gout patients with elbow joint involvement (42.9%). In all joints except metatarsophalangeal joint 1 (MTP-1), the incidence of a DCS increased by the increment of SUA levels above 7.5 mg/dl (p < 0.001). PDUS signals were most commonly found in medium and small joints and were only scarce in large joints, independent of the underlying diagnosis.

CONCLUSIONS

In our study we detected different rates of accuracy regarding DCS and PDUS in patients with acute arthritis. The best results were seen in medium-size joints, especially wrists.

2018 updated European League Against Rheumatism evidence-based recommendations for the diagnosis of gout

Although gout is the most common inflammatory arthritis, it is still frequently misdiagnosed. New data on imaging and clinical diagnosis have become available since the first EULAR recommendations for the diagnosis of gout in 2006. This prompted a systematic review and update of the 2006 recommendations. A systematic review of the literature concerning all aspects of gout diagnosis was performed. Recommendations were formulated using a Delphi consensus approach. Eight key recommendations were generated. A search for crystals in synovial fluid or tophus aspirates is recommended in every person with suspected gout, because demonstration of monosodium urate (MSU) crystals allows a definite diagnosis of gout. There was consensus that a number of suggestive clinical features support a clinical diagnosis of gout. These are monoarticular involvement of a foot or ankle joint (especially the first metatarsophalangeal joint); previous episodes of similar acute arthritis; rapid onset of severe pain and swelling; erythema; male gender and associated cardiovascular diseases and hyperuricaemia. When crystal identification is not possible, it is recommended that any atypical presentation should be investigated by imaging, in particular with ultrasound to seek features suggestive of MSU crystal deposition (double contour sign and tophi). There was consensus that a diagnosis of gout should not be based on the presence of hyperuricaemia alone. There was also a strong recommendation that all people with gout should be systematically assessed for presence of associated comorbidities and risk factors for cardiovascular disease, as well as for risk factors for chronic hyperuricaemia. Eight updated, evidence-based, expert consensus recommendations for the diagnosis of gout are proposed.

Development and Reliability of the Joint Tissue Activity and Damage Examination for Quantitation of Structural Abnormalities by Musculoskeletal Ultrasound in Hemophilic Joints

OBJECTIVES

Musculoskeletal ultrasound (US) is used increasingly to examine hemophilic arthropathy. However, quantitative algorithms to document findings are lacking. We developed and sought to validate a protocol quantifying hemophilic joint abnormalities.

METHODS

Thirty-one patients with hemophilia were examined serially for 2 years with musculoskeletal US (≈600 joint examinations and ≈6000 images). Based on the spectrum of pathologies, a quantitative algorithm, named Joint Tissue Activity and Damage Examination (JADE), was developed for soft tissue and osteochondral measurements, including power Doppler, using nominal group techniques. To study intra- and inter-rater reliability, 8 musculoskeletal US-experienced hemophilia providers performed anatomic landmark recognition and tissue measurements on 86 images with arthropathic changes, with repetition 1 month later. Twenty-three musculoskeletal US-inexperienced providers performed similar assessments. Inter-operator reliability was established by 6 musculoskeletal US-experienced hemophilia providers, each acquiring images and JADE assessments of 3 hemophilic arthropathic joints. A radiologist and musculoskeletal sonographer functioned as adjudicators. The statistical analysis was performed with the intraclass correlation coefficient (ICC), Fleiss κ, and Cohen κ where appropriate.

RESULTS

The musculoskeletal US-experienced providers showed excellent intra-and inter-rater reliability for tissue measurements (ICCs, 0.94-0.96). Agreement was good to excellent for landmark recognition (Fleiss κ, 0.87-0.94). Inter-operator reliability was excellent for measurements and landmark recognition (ICC, 0.90; Fleiss κ, 1.0). Agreement with adjudicators was mostly good to excellent. Musculoskeletal US-inexperienced providers showed excellent inter-rater reliability for measurements (ICC, 0.96) and moderate agreement for landmark recognition (Fleiss κ, 0.58).

CONCLUSIONS

The JADE protocol appears feasible for quantifying hemophilic intra-articular abnormalities. Musculoskeletal US-trained hemophilia providers showed high intra-rater, inter-rater, and inter-operator reliability, supporting JADE as a protocol for clinical management and research.

The diagnostic performance of musculoskeletal ultrasound in gout: A systematic review and meta-analysis

BACKGROUND

Musculoskeletal ultrasound is widely used in diagnosing gout, but its accuracy is debatable. We conducted a systematic review and meta-analysis to quantitatively evaluate the value of ultrasound in the diagnosis of gout.

METHODS

We systematically searched for publications using Cochrane Library, PubMed/Medline and Embase and manually screened the references of eligible articles for additional relevant publications. Studies were included in this systematic review if they assessed the diagnostic accuracy of ultrasound in gout compared to that of the gold standard, demonstration of monosodium urate crystals in joint fluid or tophi. We then conducted quantitative analyses by extracting data from each study and calculating the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR). The summary receiver operating characteristic curves (sROCs) were constructed to obtain the Q*-index and the area under the curve (AUC).

RESULTS

Thirteen studies were included in this meta-analysis. The diagnostic performances of three distinctive ultrasonographic features of gout, double contour sign (DCS), the presence of tophi and the snowstorm sign, were evaluated. For person-based evaluations, the pooled sensitivity, specificity, DOR, AUC and Q* were as follows: for the DCS, 66% (95% confidence interval (CI) 62%-69%), 92% (95% CI 90%-94%), 25.91 (95% CI 11.80-56.89), 0.8163 and 0.7503, respectively; for the presence of tophi, 56% (95% CI 52%-60%), 94% (95% CI 92%-96%), 21.11 (95% CI 7.84-56.89), 0.8928 and 0.8236, respectively; for the snowstorm sign, 31% (95% CI 27%-36%), 91% (95% CI 88%-93%), 4.54(95% CI 3.13-6.58), 0.5946 and 0.5712, respectively; and for simultaneous consideration of these ultrasonographic features, 80% (95% CI 76%-83%), 83% (95% CI 79%-86%), 19.03 (95% CI 13.97-25.93), 0.889 and 0.8197, respectively. For the joint-/location-based evaluations, the pooled sensitivity, specificity, DOR, AUC and Q* were as follows: for the DCS, 75% (95% CI 68%-80%), 65% (95% CI 59%-70%), 16.90 (95% CI 5.10-56.03), 0.871 and 0.8014, respectively; and for the presence of tophi, 48% (95% CI 40%-57%), 96% (95% CI 91%-99%), 30.20 (95% CI 9.23-98.87), 0.8776 and 0.8081, respectively.

CONCLUSIONS

In this meta-analysis, relatively high specificity but modest or low sensitivity were demonstrated in the diagnosis of gout using each of the three ultrasonographic features for person-based evaluations. Simultaneous consideration of these ultrasound findings may improve the diagnostic sensitivity. However, the double contour sign alone is weak in the differentiation of gout and non-gout for joint-/location-based evaluations. Further well-designed studies are still needed to support the current findings.

Imaging tools to measure treatment response in gout

Imaging tests are in clinical use for diagnosis, assessment of disease severity and as a marker of treatment response in people with gout. Various imaging tests have differing properties for assessing the three key disease domains in gout: urate deposition (including tophus burden), joint inflammation and structural joint damage. Dual-energy CT allows measurement of urate deposition and bone damage, and ultrasonography allows assessment of all three domains. Scoring systems have been described that allow radiological quantification of disease severity and these scoring systems may play a role in assessing the response to treatment in gout. This article reviews the properties of imaging tests, describes the available scoring systems for quantification of disease severity and discusses the challenges and controversies regarding the use of imaging tools to measure treatment response in gout.

Ultrasound scans and dual energy CT identify tendons as preferred anatomical location of MSU crystal depositions in gouty joints

OBJECTIVE

The present study was performed to localize the articular deposition of monosodium urate (MSU) crystal in joints. We compare the detection efficiencies of dual-energy CT (DECT) and ultrasound scans.

METHODS

Analyses by DECT and ultrasound were performed with 184 bilateral joints of the lower limbs of 54 consecutive gout patients. All joints were categorized into (1) knee, (2) ankle, (3) MTP1, and (4) MTP2, and sorted into those with and those without detectable MSU deposition. The comparison of the positive rate between DECT and ultrasound and the agreement was performed using the McNemar test and the Cohen's κ coefficient, respectively. Next, we listed the MSU crystal deposition as assessed by ultrasound between the DECT-positive and -negative joints according to their interior structure. We included tendons, synovia, cartilage, subcutaneous tissue, etc. RESULTS: Among all joints, the percentages with MSU crystal deposition detected by DECT (99/184, 53.8%) and ultrasound (106/184, 57.6%) were comparable (P = 0.530 > 0.05). For MTP1 (21/34, 61.8%; 12/34, 35.3%; P < 0.05) and MTP2-5 (17/34, 50.0%; 10/34, 29.4%, P < 0.05), ultrasound and DECT were more efficient, respectively. The data concordance in 46 of 50 joints (92.00%; κ = 0.769, P < 0.05) for knee; and 27 of 34 joints (79.41%; κ = 0.588, P < 0.05) for MTP2-5 and suggested that tendons were the most frequent anatomical location of MSU crystal deposition.

CONCLUSIONS

The tendons are the most frequent anatomical location of MSU crystal depositions. The concordance rate of knee joints and MTP2-5 joints shows good agreement between DECT and ultrasound depending on the location.

Role of dual-energy CT in the diagnosis and follow-up of gout: systematic analysis of the literature

The aim of this systematic review was to determine the potential role of dual-energy CT in the diagnosis and follow-up of gout with regard to the Outcome Measures in Rheumatology (OMERACT) filter. A systematic analysis of the literature was conducted using the MEDLINE and Cochrane databases and published abstracts of international congresses, according to the criteria of the OMERACT filter: feasibility, reproducibility, validity versus laboratory (serum urate, MSU synovial fluid aspirate) and other imaging modalities for gout, and its sensitivity to change in patients on urate lowering therapy (ULT). Thirty-two articles were found representing a total of 1502 patients. The data on feasibility showed that the examination took little time and involved low levels of radiation but had current limited availability. Intra- and inter-observer reproducibility was excellent, with intra-class correlation coefficients > 0.9. Validity in comparison with polarized-light microscopy showed good sensitivity and specificity (> 80%). The diagnostic performance was better than that of radiography and conventional CT-scan and at least equivalent to that of ultrasonography. The sensitivity to change varied with effect sizes from 0.05 (low) to 1.24 (high) for decrease in the tophus volume following different ULT in gout patients. Dual-energy CT-scan is a reproducible and accurate imaging modality for the diagnosis of gout, particularly for tophaceous gout (intra- or extra-articular). It can become a second-line imaging modality of choice in cases of diagnostic doubt, such as ultrasonography. Its role remains uncertain in the follow-up of gout patients treated with ULT and needs further clarification.

Potential risk factors for reactive arthritis and persistence of symptoms at 2 years: a case-control study with longitudinal follow-up

The objective of the study is to determine the risk factors for the development of reactive arthritis (ReA) and examine the factors associated with the persistence of symptoms. Patients with a new diagnosis of ReA and controls with a gastrointestinal (GI), urogenital, or sexually transmitted infection in the 3-6 months prior to study entry were prospectively enrolled in Guatemala City. ReA patients fulfilled the Assessment in Spondyloarthritis International Society criteria for peripheral spondyloarthropathy (SpA). Patients underwent history, examination, Achilles tendon ultrasound, and blood draw. Human leukocyte antigen (HLA) type and serum biomarkers were measured. t tests and nonparametric equivalents were used to examine the association of clinical, laboratory, and imaging factors with ReA. Patients were contacted 2 years later to assess for persistence of symptoms. Study subjects included patients with ReA (N = 32) and controls (N = 32). ReA patients were most frequently infected in April whereas controls were most frequently infected in August. Two ReA patients and two controls were HLA-B27-positive. Serum cathepsin K and C-reactive protein were higher in ReA patients compared to controls (p = 0.03 for both), while total cholesterol and low-density lipoprotein were lower (p = 0.008 and 0.045, respectively). Among those with ReA, 15 (47%) patients had continued symptoms at 2 years. These patients had a lower matrix metalloproteinase-3 level at diagnosis than patients for whom ReA resolved (p = 0.004). HLA-B27 was not associated with development of ReA in Guatemala; however, the month of infection was associated with ReA. The most striking finding was the persistence of arthritis at 2 years in nearly half of the patients.

Diagnostic accuracy of ultrasound in patients with gout: A meta-analysis

OBJECTIVE

This study aimed to evaluate the diagnostic performance of ultrasound (US) for patients with gout.

METHODS

We searched the Medline, Embase, Pubmed, and Cochrane Library databases, and performed a meta-analysis of the diagnostic accuracy of US according to the double contour sign, tophus, snowstorm, or bony erosion in patients with gout.

RESULTS

In total, 11 studies including 938 patients with gout, and 788 controls (patients with nongout inflammatory arthritis) were available for the meta-analysis. The pooled sensitivity and specificity of US were 65.1% ([95% confidence interval (CI): 62.0-68.2] and 89.0% (96.6-91.1), respectively. The positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 5.889 (3.365-10.30), 0.359 (0.266-0.485), and 17.61 (11.11-17.92), respectively. The area under the curve of US was 0.858 and the Q^⁎ index was 0.789, indicating good diagnostic accuracy. Some between-study heterogeneity was found in the meta-analyses. Meta-regression showed that the sample size, study design, and diagnostic criteria were not sources of heterogeneity, and subgroup meta-analyses did not change the overall diagnostic accuracy. US signs of tophus, snowstorm, or bony erosion besides the double contour sign were not sensitive (54.3%, 30.8%, and 51.6%), but specific (93.2%, 90.6%, and 93.3%) enough as a diagnostic tool.

CONCLUSIONS

Our meta-analysis of published studies demonstrates that US offers good diagnostic accuracy with high specificity and can play an important role in the diagnosis of gout.

Ultrasonography and dual-energy computed tomography provide different quantification of urate burden in gout: results from a cross-sectional study

Background

Ultrasonography (US) and dual-energy computed tomography (DECT) can assess urate burden in gout. The objective of this study was to compare the quantification of urate deposition provided by US to the one provided by DECT.

Methods

Patients with a diagnosis of gout were prospectively recruited to undergo quantification of urate deposition using US and DECT. US examination for tophi and the double contour (DC) sign was performed on the knees and feet and corresponding DECT scans provided volumes of tophi and of overall urate deposition. The primary endpoint was the intra-class correlation coefficient (ICC) of the volume of the index tophus measured by US and DECT and its 95% confidence interval (CI 95%).

Results

Of the 64 patients included, 34 presented with at least one tophus on US. DECT inter-reader agreement for urate deposition was perfect with an ICC of 1 (1–1) and good for the measurement of the index tophus with an ICC of 0.69 (0.47–0.83). The ICC for the measurement of the index tophus between the two techniques was poor with a value of 0.45 (0.1–0.71). The average ratio between the index tophi volume as assessed by DECT and US was 0.65. The number of DC-positive joints did not correlate with DECT volume of overall deposits (Spearman correlation coefficient of 0.23).

Conclusions

DECT measurements of tophi give smaller volumes to the same tophi measured with US, and US signs of urate deposition in joints do not correlate with overall DECT volumes of extra-articular deposition.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1381-2) contains supplementary material, which is available to authorized users.

Performance of Ultrasound in the Diagnosis of Gout in a Multicenter Study: Comparison With Monosodium Urate Monohydrate Crystal Analysis as the Gold Standard

OBJECTIVE

To examine the performance of ultrasound (US) for the diagnosis of gout using the presence of monosodium urate monohydrate (MSU) crystals as the gold standard.

METHODS

We analyzed data from the Study for Updated Gout Classification Criteria (SUGAR), a large, multicenter observational cross-sectional study of consecutive subjects with at least 1 swollen joint who conceivably may have gout. All subjects underwent arthrocentesis; cases were subjects with confirmed MSU crystals. Rheumatologists or radiologists who were blinded with regard to the results of the MSU crystal analysis performed US on 1 or more clinically affected joints. US findings of interest were double contour sign, tophus, and snowstorm appearance. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Multivariable logistic regression models were used to examine factors associated with positive US results among subjects with gout.

RESULTS

US was performed in 824 subjects (416 cases and 408 controls). The sensitivity, specificity, PPV, and NPV for the presence of any 1 of the features were 76.9%, 84.3%, 83.3%, and 78.2%, respectively. Sensitivity was higher among subjects with a disease duration of ≥2 years and among subjects with subcutaneous nodules on examination (suspected tophus). Associations with a positive US finding included suspected clinical tophus (odds ratio [OR] 4.77 [95% confidence interval (95% CI) 2.23-10.21]), any abnormality on plain radiography (OR 4.68 [95% CI 2.68-8.17]), and serum urate level (OR 1.31 [95% CI 1.06-1.62]).

CONCLUSION

US features of MSU crystal deposition had high specificity and high PPV but more limited sensitivity for early gout. The specificity remained high in subjects with early disease and without clinical signs of tophi.

An optimal ultrasonographic diagnostic test for early gout: A prospective controlled study

Objective

To identify the optimal sites for classification of early gout by ultrasonography.

Methods

Sixty patients with monosodium urate crystal-proven gout (25 with early gout [≤2-year symptom duration], 35 with late gout [>2-year symptom duration], and 36 normouricemic healthy controls) from one centre were prospectively evaluated. Standardized blinded ultrasound examination of 36 joints and the triceps and patellar tendons was performed to identify tophi and the double contour (DC) sign.

Results

Ultrasonographic sensitivity was lower in early than late gout. Binary logistic regression analysis showed that two ultrasonographic signs (tophi in the first metatarsophalangeal joint [odds ratio, 16.46] and the DC sign in the ankle [odds ratio, 25.18]) significantly contributed to the final model for early gout diagnosis (sensitivity and specificity of 84% and 81%, respectively). The inter-reader reliability kappa value for the DC sign and tophi was 0.712.

Conclusions

Four-joint investigation (both first metatarsophalangeal joints for tophi and both ankles for the DC sign) is feasible and reliable and could be proposed as a screening test for early ultrasonographic gout classification in daily practice.

Ultrasound Features of the First Metatarsophalangeal Joint in Gout and Asymptomatic Hyperuricemia: Comparison With Normouricemic Individuals

OBJECTIVE

The first metatarsophalangeal (MTP1) joint is frequently affected in gout. The aim of this study was to identify ultrasound features of the MTP1 joint in people with gout and people with asymptomatic hyperuricemia compared with normouricemic controls.

METHODS

Participants with gout (n = 23) and asymptomatic hyperuricemia (n = 29), and age- and sex-matched normouricemic control participants (n = 34), underwent a gray-scale and power Doppler ultrasound assessment of bilateral MTP1 joints by a single musculoskeletal radiologist. No participants had clinical evidence of joint inflammation at the time of scanning. The static images were later read by 2 musculoskeletal radiologists for the presence of the double contour sign, tophus, erosion, effusion, synovial hypertrophy, synovitis, and cartilage thickness.

RESULTS

Compared to normouricemic control participants, participants with gout and participants with asymptomatic hyperuricemia had more frequent double contour sign (odds ratio [OR] 3.91, P = 0.011 and OR 3.81, P = 0.009, respectively). Participants with gout also had more erosion (OR 10.13, P = 0.001) and synovitis (OR 9.00, P < 0.001) and had greater tophus and erosion diameters (P = 0.035 and P < 0.001, respectively). More severe erosion and synovitis grades and a less severe effusion grade were independently associated with gout compared with asymptomatic hyperuricemia (R²  = 0.65, P < 0.001).

CONCLUSION

Urate deposition, synovitis, and bone erosion are common at the MTP1 joint in people with gout, even in the absence of flare. Although individuals with asymptomatic hyperuricemia lack ultrasound features of inflammation or structural joint changes, they demonstrate a similar frequency of urate deposition.

[Gout - new approaches to diagnostics and treatment]

An attack of gout is extremely painful. Recurrent attacks of arthritis in one or more joints or tendon sheaths accompanied by intense pain are typical of this commonly occurring condition. As these symptoms indicate acute inflammation due to uric acid crystal deposition, good diagnostics are essential to enable initiation of drug treatment which removes the crystals deposited in tissue.

Ultrasound as an Outcome Measure in Gout. A Validation Process by the OMERACT Ultrasound Working Group

OBJECTIVE

To summarize the work performed by the Outcome Measures in Rheumatology (OMERACT) Ultrasound (US) Working Group on the validation of US as a potential outcome measure in gout.

METHODS

Based on the lack of definitions, highlighted in a recent literature review on US as an outcome tool in gout, a series of iterative exercises were carried out to obtain consensus-based definitions on US elementary components in gout using a Delphi exercise and subsequently testing these definitions in static images and in patients with proven gout. Cohen's κ was used to test agreement, and values of 0-0.20 were considered poor, 0.20-0.40 fair, 0.40-0.60 moderate, 0.60-0.80 good, and 0.80-1 excellent.

RESULTS

With an agreement of > 80%, consensus-based definitions were obtained for the 4 elementary lesions highlighted in the literature review: tophi, aggregates, erosions, and double contour (DC). In static images interobserver reliability ranged from moderate to almost perfect, and similar results were found for the intrareader reliability. In patients the intraobserver agreement was good for all lesions except DC (moderate). The interobserver agreement was poor for aggregates and DC but moderate for the other components.

CONCLUSION

These first steps in evaluating the validity of US as an outcome measure for gout show that the reliability of the definitions ranged from moderate to excellent in static images and somewhat lower in patients, indicating that a standardized scanning technique may be needed, before testing the responsiveness of those definitions in a composite US score.

The OMERACT Ultrasound Working Group 10 Years On: Update at OMERACT 12

Musculoskeletal ultrasound (US) now thrives as an established imaging modality for the investigation and management of chronic inflammatory arthritis. We summarize here results of the Outcome Measures in Rheumatology (OMERACT) US working group (WG) projects of the last 2 years. These results were reported at the OMERACT 12 meeting at the plenary session and discussed during breakout sessions. Topics included standardization of US use in rheumatic disease over the last decade and its contribution to understanding musculoskeletal diseases. This is the first update report of WG activities in validating US as an outcome measure in musculoskeletal inflammatory and degenerative diseases, including pediatric arthritis, since the OMERACT 11 meeting.