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

Systematic literature review to inform the EULAR recommendations for the use of imaging in crystal-induced arthropathies in clinical practice

OBJECTIVE

To summarise current data regarding the use of imaging in crystal-induced arthropathies (CiAs) informing a European Alliance of Associations for Rheumatology task force.

METHODS

We performed four systematic searches in Embase, Medline and Central on imaging for diagnosis, monitoring, prediction of disease severity/treatment response, guiding procedures and patient education in gout, calcium pyrophosphate dihydrate deposition (CPPD) and basic calcium phosphate deposition (BCPD). Records were screened, manuscripts reviewed and data of the included studies extracted. The risk of bias was assessed by validated instruments.

RESULTS

For gout, 88 studies were included. Diagnostic studies reported good to excellent sensitivity and specificity of dual-energy CT (DECT) and ultrasound (US), high specificity and lower sensitivity for conventional radiographs (CR) and CT. Longitudinal studies demonstrated sensitivity to change with regard to crystal deposition by US and DECT and inflammation by US and structural progression by CR and CT. For CPPD, 50 studies were included. Diagnostic studies on CR and US showed high specificity and variable sensitivity. There was a single study on monitoring, while nine assessed the prediction in CPPD. For BCPD, 56 studies were included. There were two diagnostic studies, while monitoring by CR and US was assessed in 43 studies, showing a reduction in crystal deposition. A total of 12 studies with inconsistent results assessed the prediction of treatment response. The search on patient education retrieved two studies, suggesting a potential role of DECT.

CONCLUSION

This SLR confirmed a relevant and increasing role of imaging in the field of CiAs.

Metabolic syndrome and psoriatic arthritis: the role of weight loss as a disease-modifying therapy

Psoriatic arthritis (PsA) is an inflammatory joint and entheseal disease associated with significant personal and public health burden. PsA has a prevalence of up to 1%, affecting ~20% of people suffering with psoriasis. PsA is frequently accompanied by metabolic syndrome (MetS), and both conditions are characterised by a chronic pro-inflammatory state, with several key cytokines in PsA (interleukin (IL)-17 and IL-23) also elevated in those with MetS. This narrative review aims to provide an update on MetS in PsA, focusing on its prevalence, pathogenesis, prognosis, treatment interactions and future therapeutic options. MetS is particularly prevalent in PsA compared to other inflammatory arthritides. Cohort studies indicate a higher risk of PsA in individuals with obesity, while Mendelian randomization studies link childhood obesity, insulin resistance, and dyslipidaemia to PsA. Weight loss interventions have been shown to reduce disease activity in PsA. Additionally, MetS negatively impacts the efficacy of tumour necrosis factor inhibitor (TNFi) drugs in treating PsA. Drugs given for PsA may also affect the conditions constituting MetS. Leflunomide has been shown to reduce body weight but also increase blood pressure. TNFi drugs lead to weight gain but reduce cardiovascular risk. Janus kinase inhibitors increase lipid levels and cardiovascular risk among high-risk groups. Anti-IL-17 and anti-IL-12/IL-23 drugs may cause a short-term increase in cardiovascular risk, although the long-term effects have yet to be established. Weight loss represents an unexplored avenue for disease modification in PsA, alongside a plethora of general health benefits. Dietary and exercise modifications are the cornerstone of weight management but vary substantially across individuals. Novel therapies to treat weight loss, such as glucagon-like peptide 1 agonists and sodium-glucose cotransporter 2 inhibitors, may prove useful alongside disease-modifying therapies for those with PsA and MetS and should be investigated as potential therapeutic adjuncts.

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.

Single photon emission computed tomography/computed tomography imaging of gouty arthritis: A new voice

Gouty arthritis, often referred to simply as gout, is a disorder of purine metabolism characterized by the deposition of monosodium urate monohydrate (MSU) crystals in multiple systems and organs, especially in joints and their surrounding soft tissue. Gout is a treatable chronic disease, and the main strategy for effective management is to reverse the deposition of MSU crystals by uric acid reduction, and to prevent gout attacks, tophi deposition and complications, and thereby improve the quality of life. However, the frequent association of gout with other conditions such as hypertension, obesity, cardiovascular disease, diabetes, dyslipidemia, chronic kidney disease (CKD) and kidney stones can complicate the treatment of gout and lead to premature death. Here, we review the use of medical imaging techniques for studying gouty arthritis with special interest in the potential role of single photon emission computed tomography (SPECT)/computed tomography (CT) in the clinical management of gout and complications (e.g., chronic kidney disease and cardiovascular disease).

Interest in daily clinical practice of screening for gouty disease in patients with psoriatic arthritis

Objectives

PsA and gout are two prevalent rheumatic diseases, that can be associated as part of a rheumatism known as 'Psout'. Both conditions are associated with cardiovascular (CV) risk, thus their co-occurrence could have significant implications for the management of CV risks and patient care. This study aimed to determine the prevalence of gout within a PsA patient cohort and, consequently, to identify factors associated with this pathological association.

Methods

This is an observational, descriptive, cross-sectional, single-center study, including patients diagnosed with PsA. Demographic, clinical, biological and imaging data were collected. We identified the proportion of patients simultaneously affected by PsA and gout and compared characteristics between those with and without gout.

Results

The prevalence of gout among PSA patients was 9.8% (12/122), with a prevalence of 23% for asymptomatic hyperuricemia and 7.4% presenting with specific US signs of gout. Significant associated factors in the univariate analysis included weight, hypertension, diabetes, certain medications (diuretics, aspirin, lipid-lowering agents), impaired renal function, elevated fasting blood glucose, lipid abnormalities and specific US signs of gout.

Conclusion

Our study has described the existence of patients simultaneously affected by PsA and gout ('Psout'). Performing joint US along with uric acid level measurements in PsA patients can enable personalized therapeutic care.

The association between gout flares and monosodium urate burden assessed using musculoskeletal ultrasound in patients with gout

Background

Ultrasound (US) has a high sensitivity in detecting monosodium urate (MSU) deposition in gout patients. However, the value of US in predicting gout flares has been reported only in a few monocentric studies.

Objective

To investigate the association between gout flares in the previous year and US-detected MSU burden using two different US scores.

Design

A retrospective study.

Methods

Patients with gout were consecutively recruited to undergo musculoskeletal US examinations of their knees, ankles, and feet. The score derived from Outcome Measure in Rheumatology (hereinafter referred to as MSU score) and musculoskeletal US features-based (hereinafter referred to as MSKF score) were used to quantify the MSU burden of gout. Odds ratios for frequent gout flares were calculated.

Results

We enrolled 1894 patients with gout (mean age: 45 years; gout duration: 5 years; males: 96.1%), experiencing a median of three flares over the past year. Of these, 428 (22.6%) patients reported frequent (⩾7) gout flares. The MSU and MSKF median scores were 6 and 9, respectively. For each five-point increase in MSU and MSKF score, the odds ratio of frequent gout flares increased 1.13-fold and 1.24-fold, respectively. The area under the curve (AUC) for the MSU and MSKF score was 0.635 [95% confidence interval (CI): 0.604-0.665] and 0.688 (95% CI: 0.659-0.718), respectively, (AUC difference 0.054, p value for AUC difference < 0.001).

Conclusion

The MSU and MSKF scores were significantly associated with the number of gout flares in the previous year. The MSKF score outperformed the MSU score in terms of frequent gout flare discrimination.

Periosteal Manifestations of Osteomyelitis and Arthritis on Ultrasound: A Systematic Review

Ultrasound (US) can visualize the periosteal changes in the early stage compared to radiography. In this review, we studied periosteal manifestations on US and assessed their diagnostic utility for osteomyelitis (OM) and arthritis. We included articles that studied ultrasonographic findings of periosteal changes in OM and arthropathies with aims to systematically review periosteal manifestations of each condition and summarize diagnostic values of each finding. A total of 13 articles were included in the systematic review. Of these, 10 articles are on OM, 3 articles are on psoriatic arthritis (PsA), 1 article is on rheumatoid arthritis (RA), and 1 article is on gouty arthritis (GA). In OM, subperiosteal fluid/subperiosteal collection (SF/SC) was detected in 32%-76% within 72 h after presentation. Periosteal reaction (PR) was seen after day 4 and the sensitivity on US ranges from 33% to 100%. In PsA, PR was seen near 16%-59% in active PsA joints. Periosteal changes are rarely detected in RA joints. Small hyperechoic spots were seen in 87.5% of GA. SF/SC may be seen on US as the earliest sign followed by PR for OM. PR is more specific in PsA than RA. Further investigations on periosteal abnormalities on US are warranted to confirm our findings.

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.

Time to redefine hyperuricemia? The serum uric acid cut-off level for precipitation might be lower: a pilot study

BACKGROUND

Hyperuricemia is classically defined as serum uric acid (SUA) value higher than 6.8 mg∕dL; between hyperuricemic patients, only 15-20% will develop gout. Our first goal was to find if there is a specificity of the "snowstorm" feature on ultrasound (US) for hyperuricemia. Moreover, we aimed to determine if there is a level of SUA from which the urates tend to appear in the synovial fluid, without generating a typical clinical gouty flare.

PATIENTS, MATERIALS AND METHODS

We conducted a cross-sectional, transverse study, including 108 consecutive patients that displayed a set of clinical and imaging features, such as swollen knee and US proof for knee joint effusion.

RESULTS

Performing binary logistic regression, the relation between the explanatory variable (hyperechogenic spots) and the response variable (SUA) was demonstrated to be a significant one (p=0.005). The value of 0.397 for the statistical phi coefficient suggests a medium intensity association between the diagnosis of gout or asymptomatic hyperuricemia and whether the patients have hyperechogenic spots or not. We found the cut-off value for SUA equal to 4.815 mg∕dL, regardless of gender, from which, the urate starts to precipitate. Values for men tend to be higher in comparison to the ones found for women (4.95 mg∕dL vs. 3.9 mg∕dL).

CONCLUSIONS

The "snowstorm" aspect of the fluid might be the result of an increased level of SUA and more than this, the cut-off level for SUA to precipitate might be lower than the fore used values.

How can ultrasonography help in the management of CPPD? From diagnosis to clinical subset identification

PURPOSE OF REVIEW

Clinical manifestations of calcium pyrophosphate deposition (CPPD) disease are quite heterogeneous, ranging from asymptomatic presentation to severe forms of arthritis. In recent years, imaging, particularly ultrasound (US) has gained a central role for the diagnosis of CPPD. However, many questions are still open. Aim of this review is to present how US could be a key tool in the diagnosis and assessment of CPPD and for the identification of subsets of the disease.

RECENT FINDINGS

awareness and research interest around CPPD is increasing in the recent years, as several international taskforces are working on the validation of outcome measures and classification criteria for CPPD, but many pieces of the puzzle are still missing. Recent studies demonstrated that CPPD is an underdiagnosed disease, frequently misdiagnosed as rheumatoid arthritis or polymyalgia rheumatica. US has been increasingly used in the past decade for the diagnosis of CPPD and US definitions have been validated by the OMERACT US working group in the recent years, making of US a valuable tool for diagnosis.

SUMMARY

The most challenging aspects of CPPD are the differential diagnosis with other form of arthritis of the elderly, and the classification of patients in clinical subsets. In this review, we will present the available data for the use of US in the diagnosis of CPPD and we will provide a mainly experienced-based approach to the potential role of the technique in differential diagnosis and phenotypization of patients.

Dynamic assessment of the double contour sign by ultrasonography helps to distinguish between gout and calcium pyrophosphate deposition disease

OBJECTIVE

To test whether the double contour (DC) sign has a different dynamic behaviour in gout and calcium pyrophosphate deposition (CPPD) and whether the dynamic assessment of the DC sign increases its accuracy in gout diagnosis.

METHODS

This cross-sectional analysis included patients with gout meeting the 2015 ACR/EULAR classification criteria and patients with crystal-proven diagnosis of CPPD. Hyaline cartilages were explored by ultrasound (US) to detect the DC sign (ie, abnormal hyperechoic band over the superficial margin of hyaline cartilages) and its dynamic behaviour during joint movement was evaluated ((ie, movement of the DC sign together with subchondral bone (DC sign), or in the opposite direction (pseudo DC sign)).

RESULTS

Eighty-one patients with gout and 84 patients with CPPD underwent US assessment. Among them, 47 patients with gout and 9 patients with CPPD had evidence of the DC sign. During dynamic assessment, in all 47/47 patients with gout there was a DC sign. Conversely, in 7/9 (77.8%) patients with CPPD, there was a pseudo DC sign (p<0.01).The presence of DC sign during static assessment had a sensitivity, specificity and accuracy of 58.0% (95% CI 46.5% to 68.9%), 89.3% (95% CI 80.6% to 95.0%) and 73.9% (95% CI 66.5% to 80.5%) for gout, respectively. The dynamic evaluation improved the DC sign's diagnostic performance (p=0.01) as the specificity (97.6% (95% CI 91.7% to 99.7%)) and the accuracy (78.2% (95% CI 71.1% to 84.2%)) increased without loss in sensitivity.

CONCLUSION

The dynamic US assessment of the DC sign may help to differentiate the DC sign due to MSU crystals from the pseudo DC sign seen in CPPD, as they move in opposite directions.

Mnemonics and Metaphorical Videos for Detecting/Diagnosing Musculoskeletal Sonopathologies

ABSTRACT

Musculoskeletal ultrasound identifies a broad range of pathologies. Typical sonographic images of certain pathological/abnormal conditions can be rendered and "highlighted" for the daily practice/language of musculoskeletal sonographers. The following text and accompanying figures/videos represent a collection of findings pertaining to commonplace pathological conditions. This article is the second part of a series-after the characteristic/metaphoric descriptions of normal musculoskeletal structures.

Orthopaedic Management of Gout

Gout is characterized by the deposition of monosodium urate crystals in patients with chronically elevated blood levels of uric acid. It is the most common form of inflammatory arthritis in the United States and is often comorbid with hypertension, obesity, and chronic kidney disease. Initial presentation is usually an acutely warm, swollen joint, most commonly the first metatarsophalangeal joint, but a variety of locations may be affected. The main treatment for gout is medical management of acute inflammation and chronic uric acid levels, but surgical treatment may be indicated in cases of damage to the surrounding soft tissue, concomitant septic arthritis, symptomatic cartilage loss, or neurologic deficits. Based on the literature to date, gout does not seem to independently affect outcomes after total hip, knee, and ankle arthroplasty, but associated comorbidities affecting outcomes in these patients should be considered.

North American musculoskeletal ultrasound scanning protocol of the shoulder, elbow, wrist, and hand: update of a Delphi Consensus Study

INTRODUCTION/OBJECTIVES

There has been an increase in the proficiency and utilization of ultrasound among North American rheumatologists over the past decade. This study aims to create an updated upper extremity scanning protocol to inform ultrasound curriculum development for the American College of Rheumatology affiliated fellowship programs and guide clinical practice patterns in North America.

METHOD

Three Delphi survey rounds were used to reach consensus on tiered-mastery designations for scan views of the shoulder, elbow, wrist, and hand joints. The survey was disseminated by Qualtrics™ to 101 potential participants with ultrasound experience. High agreement was defined as having ≥ 85% consensus and final tier designation as > 50% agreement for a preferred tier. Changes in responses were evaluated by McNemar's chi-square test.

RESULTS

Consensus was achieved for 70% of scan views of the upper extremity joints. Two views-ulnar transverse view of the wrist and the radial/ulnar orthogonal views over metacarpophalangeal joints 2 and 5 of the hand-were upgraded from tier 2 to tier 1. The suprascapular transverse and the axillary longitudinal views of the shoulder were downgraded from tier 2 to tier 3. A new anterior transverse view of the elbow was added to the protocol with tier 1 designation.

CONCLUSIONS

This study reflects the current opinions of North American rheumatologists for scanning upper extremity joints and provides support for the updated protocol and guidance for educators in rheumatology ultrasound. Key Points • Ultrasound scan views of the metacarpophalangeal, wrist, elbow, and glenohumeral joint recesses and views of the biceps and rotator cuff tendons at the shoulder were perceived as essential views of the upper extremity scanning protocol for rheumatologists to master and perform routinely. • A targeted scanning approach of the upper extremity joints may be considered when focal symptoms are present. • The North American Musculoskeletal Ultrasound Scanning Protocol shares some similarities with existing musculoskeletal ultrasound protocols of other specialties and worldwide rheumatology societies but varies in the extent of examination and emphasis on certain specialty-specific focuses.

Periarticular calcifications

Periarticular calcification and ossification is a frequent finding on imaging and may sometimes pose a diagnostic challenge. The differential diagnoses for this radiological finding are wide and can be classified into broad groups such as idiopathic, developmental, trauma, burns, infection, tumor, connective tissue disease, crystalline, metabolic, vascular, and foreign bodies. With careful consideration of the clinical and imaging findings as well as awareness of mimickers of periarticular mineralization, the list of differential diagnoses can be narrowed down. This article aims to review the clinical-radiologic findings of periarticular calcified or ossified lesions with relevant imaging illustrations.

The Use of Ultrasound to Differentiate Between Gout and Infection in the Wrist

Background:

Gout is a common condition and its prevalence is increasing. In the wrist, acute gouty arthritis is difficult to distinguish from infection and may occur concomitantly. Though aspiration is helpful, it is not always technically feasible or definitive. Imaging may assist in the differential diagnosis.

Case Presentation:

Two cases are described in which the use of ultrasound evaluation assisted in the diagnosis and ultimate treatment.

Conclusion:

Ultrasound can be a helpful adjunct in the diagnosis of arthritis of the wrist, helping to tailor treatment in complex cases.

The Role of Advanced Imaging in Gout Management

Gout is a common form of inflammatory arthritis where urate crystals deposit in joints and surrounding tissues. With the high prevalence of gout, the standardized and effective treatment of gout is very important, but the long-term treatment effect of gout is not satisfied because of the poor adherence in patients to the medicines. Recently, advanced imaging modalities, including ultrasonography (US), dual-energy computed tomography (DECT), and magnetic resonance imaging (MRI), attracted more and more attention for their role on gout as intuitive and non-invasive tools for early gout diagnosis and evaluation of therapeutic effect. This review summarized the role of US, DECT, and MRI in the management of gout from four perspectives: hyperuricemia, gout attacks, chronic gout, and gout complications described the scoring systems currently used to quantify disease severity and discussed the challenges and limitations of using these imaging tools to assess response to the gout treatment.

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.

Gouty Arthropathy: Review of Clinical Manifestations and Treatment, with Emphasis on Imaging

Gout, a crystalline arthropathy caused by the deposition of monosodium urate crystals in the articular and periarticular soft tissues, is a frequent cause of painful arthropathy. Imaging has an important role in the initial evaluation as well as the treatment and follow up of gouty arthropathy. The imaging findings of gouty arthropathy on radiography, ultrasonography, computed tomography, dual energy computed tomography, and magnetic resonance imaging are described to include findings of the early, acute and chronic phases of gout. These findings include early monosodium urate deposits, osseous erosions, and tophi, which may involve periarticular tissues, tendons, and bursae. Treatment of gout includes non-steroidal anti-inflammatories, colchicine, glucocorticoids, interleukin-1 inhibitors, xanthine oxidase inhibitors, uricosuric drugs, and recombinant uricase. Imaging is critical in monitoring response to therapy; clinical management can be modulated based on imaging findings. This review article describes the current standard of care in imaging and treatment of gouty arthropathy.

Reliability of knee joint sonography in the evaluation of gouty arthritis

Objective: To determine the reliability of knee joint sonography in the evaluation of gouty arthritis. Methodology: A search of Google Scholar, PubMed, NCBI, MEDLINE, and Medscape databases, from 1988 up to 2020. The key search terms used were knee joint; knee joint ultrasound; gout; gouty arthritis, knee joint pain; sensitivity; specificity. The reviewer independently screened the titles and abstracts of the relevant articles and full-text downloads to determine whether the inclusion or exclusion criteria were met. Results: In total, 103 articles were identified through the database search. In addition, 11 articles were identified through other sources. Then, screening was performed, and 9 articles were removed due to duplication. Further screening was done for 105 articles, and 27 articles were excluded due to insufficient information. Seventy-eight full-text articles were assessed for eligibility. A total of 13 full-text articles were excluded due to research performed on animals, as the study had been designed as a review of only human studies. Sixty-three studies were included that had a qualitative synthesis. Conclusion: The knee is a weight-bearing joint and may be affected by a myriad of different pathological conditions, therefore a proper diagnosis is of prime importance for a proper management plan. Ultrasound is a non-invasive, radiation-free, and readily available modality that has high sensitivity and specificity in the evaluation of gouty arthritis.

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.

Monoarticular Crystal Arthropathy of the Knee: Tophaceous Gout

Tophaceous gout is a crystal arthropathy and a disorder of purine metabolism characterized by monosodium urate crystal deposition. A case of tophaceous gout of the knee joint in a 30-year-old female is reported, and the imaging appearances on high-resolution ultrasonography are described. The patient presented with complaints of insidious onset painless swelling of the left knee joint with limitation of range of movement for 1 week. The aspirated joint fluid demonstrated needle-like monosodium urate crystals showing strong negative birefringence consistent with a diagnosis of tophaceous gout. Targeted urate-lowering treatment included oral nonsteroidal anti-inflammatory drugs and oral colchicine. Prophylactic treatment for gout flare-ups included initiation of allopurinol at 300 mg/day along with modification of the dietary regimen including limited consumption of red meat and increased consumption of low-fat dairy products. Symptomatic improvement with reduced pain and swelling of the knee joint was noted at 10 days after treatment. Subsequently, at 3-month follow-up, the patient was disease free with no signs of recurrence and serum uric acid levels at 3.7 mg/dL. In spite of a wide range of therapeutic options available for the management of tophaceous gout, suboptimal management of gout is prevalent till date in both developing and developed nations across the world.

Differential Diagnosis of Acute and Chronic Gouty Arthritis by Multijoint Ultrasound

To investigate whether multi-joint ultrasound (US) findings in patients with gouty arthritis could be used to distinguish between acute and chronic stages, we performed a retrospective study with 129 enrolled patients from the Rheumatology Department of the First Affiliated Hospital of Chengdu Medical College from September 1, 2018 to June 12, 2019. Patients with acute or non-acute gout were categorized using clinical data, and US imaging findings of the knees, ankles and first metatarsophalangeal joints were analyzed and compared between groups. Notably, we found that the most prevalent sign detected by US was the hyperechoic spot in the synovium, followed by arthrosynovitis, aggregates, double contour signs and tophi; meanwhile, bone erosions were the least common. Additionally, synovitis was more frequently detected in the acute joints of gouty arthritis (49%) compared with the non-acute joints (35%), whereas grade 1 or 2 blood flow classifications (97%), tophi and bone lesions were more often seen in the latter. Overall, our data suggest that multi-joint US scanning might be used to evaluate disease severity and discriminate between stages of gouty arthritis.

Limitations of dual-energy CT in the detection of monosodium urate deposition in dense liquid tophi and calcified tophi

OBJECTIVE

Dual-energy CT (DECT) detection of monosodium urate (MSU) crystal deposition has demonstrated good sensitivity and specificity in patients with established gout. However, limitations have been reported with early disease and with low urate burden. We aimed to study the performance of DECT in the detection and quantification of MSU deposition in solid and liquid tophi.

MATERIALS AND METHODS

Patient-derived solid and liquid tophi, suspensions of commercial synthetic, and in-house synthetic MSU crystals were prepared at varying concentrations. DECT was performed at 80 kVp and 150 kVp, and post-processed using Syngo Via gout software (Siemens) that color-coded urate and cortical bone as green and purple, respectively. DECT findings were correlated with ultrasound and microscopic findings. The protocol was reviewed by IRB and considered a non-human subject research.

RESULTS

DECT did not detect urate deposition in either patient-derived liquid tophi or in-house synthetic crystals at any concentration. Lowering the post-processing minimum threshold increased the detection of in-house synthetic crystals but did not change the detection of patient-derived liquid tophi. Areas of calcium-rich purple color-coded regions, masking detection of urate, within the solid tophi and surrounding liquid tophi were noted on DECT. Histology showed co-presence of calcium along with MSU deposition in these.

CONCLUSION

This study illustrates important limitations of DECT for liquid tophi due to subthreshold CT attenuation and for calcified tophi due to the obscuration of urate by calcium. Urate may be either undetectable or underestimated by DECT when these conditions are present.

What Has Dual Energy CT Taught Us About Gout?

PURPOSE OF THE REVIEW

Dual energy computed tomography (DECT) scan has emerged as a useful diagnostic tool in the diagnosis of gout over recent years. Here, we review the role of DECT in the context of typical and atypical gout, including its role in identifying extra-articular monosodium urate (MSU) deposition.

RECENT FINDINGS

DECT has been found to be more accurate than ultrasound in detecting extra-articular MSU deposition in soft tissue. It has the ability to identify axial MSU deposition in gout patients with non-specific back pain. For individuals with no other clear etiology, this potentially implicates MSU as the cause of the pain. DECT also has the ability to detect vascular MSU deposition. This correlates with high coronary calcium scores and elevated Framingham cardiovascular risk. DECT continues to aid our understanding of articular and extra-articular MSU deposition, including the role of vascular MSU deposition on cardiovascular health. Not only does it allow quantification of urate burden but it can also potentially avoid invasive diagnostic procedures. The limitations and advantages of DECT are further explored in this article.

Sonographic estimation of monosodium urate burden predicts the fulfillment of the 2016 remission criteria for gout: a 12-month study

Objective

To investigate whether baseline monosodium urate (MSU) burden estimated by ultrasound (US) predicts the achievement of the 2016 remission criteria for gout after 12 months.

Methods

In this 12-month prospective, observational and single-center study, patients with gout fulfilling all the domains of the 2016 preliminary remission criteria for gout at baseline and on urate-lowering therapy (ULT) for at least the preceding 6 months were consecutively enrolled.

The US findings indicative of MSU deposits [aggregates, double contour (DC) sign, and/or tophi] were identified according to the Outcome Measure in Rheumatology US Working Group definitions.

The US MSU burden was estimated by evaluating elbows, wrists, 2nd metacarpophalangeal joints, knees, ankles, and 1st metatarsophalangeal joints.

Results

Remission criteria were fulfilled in 21 (42.0%) out of 50 patients at 12 months. The baseline US MSU burden was significantly lower in patients who achieved remission than in those who did not fulfill the remission criteria at 12 months (1.9±1.8 vs 5.1±3.1, p<0.01).

US scores and ongoing flare prophylaxis were the only significant predictors of remission with an odds ratio of 10.83 [(95%CI=1.14–102.59), p=0.04] for the absence of MSU deposits, 5.53 [(95%CI=1.34–22.76), p<0.01] for the absence of aggregates, 7.33 [(95%CI=1.71–31.44), p<0.01] for the absence of DC sign, 3.88 [(95%CI=1.08–13.92), p=0.04] for the absence of tophi, and 0.23 [(95%CI=0.07–0.75), p=0.02] for ongoing flare prophylaxis.

Conclusion

In gout, baseline US estimation of MSU burden is an independent predictor of the achievement of the remission criteria at 12 months.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02568-x.

What is the diagnostic value of dual-energy computed tomography in patients with clinical diagnosis of gout?

OBJECTIVES

To investigate the frequency of monosodium urate (MSU) crystal deposits on dual-energy computed tomography (DECT) in patients with clinical diagnosis of gout and the factors associated MSU crystal positivity.

METHODS

This study was conducted in patients with clinical diagnosis of gout who underwent DECT. Clinical features were compared between patients with positive and those with negative DECT results. A logistic regression analysis was performed to determine the factors associated with MSU crystal positivity on DECT.

RESULTS

A total of 148 patients with clinical diagnosis of gout were included, and MSU crystal deposition on DECT was observed in 64 patients (43.3%). The patients with positive DECT results were more likely to have renal insufficiency, longer disease duration, and higher serum urate level than those with negative. In the multivariable analysis, first gout attack (odds ratio 0.462; 95% confidence interval 0.229-0.931, p = 0.031) was associated with a less likely MSU crystal deposit-positive DECT result. In the subgroup analysis of patients with first attack, serum urate level > 8 mg/dL was associated with DECT positivity.

CONCLUSION

Of the patients with clinical diagnosis of gout, those with renal insufficiency, longer disease duration, and high serum urate level were more likely to be positive of gout on DECT. First gout attack was associated with less likely to be positive for MSU crystal on DECT. Thus, performing DECT scan in the selected patients who had characteristics that highly probability of DECT positivity could increase positive predictive value.

Unravelling the mysteries of gout by multimodality imaging

Gout is a common inflammatory arthritis that manifests as an aggregate of variably symptomatic monosodium urate crystals (MSU) in the joints and surrounding tissues in addition to multisystem involvement such as genitourinary and cardiovascular systems. In recent decades, there has been a documented increase in the prevalence and incidence of gout. Risk factors for gout include obesity, dietary influences, hypertension, renal impairment, and diuretic use. A prompt diagnosis followed by uric acid lowering treatment prior to the onset of bone destruction is the goal in any suspected case of gout. Advanced imaging modalities, such as dual energy computed tomography (DECT) and ultrasonography (US), employed for the diagnosis of gout are each accompanied by advantages and disadvantages. Conventional radiography (CR), although useful in visualizing joint erosions and mineralization, is limited in its ability to diagnose gout flare. Although synovial fluid aspiration remains the gold standard for MSU crystal visualization, less-invasive imaging modalities are preferred to avoid potential complications. DECT and US in particular are useful in the diagnosis of gout. In this review, we will discuss the current state and role of imaging in the detection of gout.

Hand Masses

Hand and wrist soft tissue masses may be classified as pseudotumors, benign neoplasms, or malignant neoplasms. The vast majority of hand lesions are benign. Consideration of the location of the lesion and its imaging characteristics often leads to a specific diagnosis. Pseudotumors discussed in this article are ganglion cysts, accessory muscles, and inflammatory lesions. True tumors are described according to their tissue type: nerve sheath tumors, adipocytic tumors, so-called fibrohistiocytic tumors, pericytic tumors, and vascular lesions. We also outline the imaging features of masses encountered in the hand and wrist.

Radiologic Imaging of Metabolic and Endocrine Disorders as They Affect the Hand and Wrist

Metabolic and endocrine disorders have systemic effects on the musculoskeletal system, frequently producing characteristic changes in the hand and wrist. Radiographs historically played an instrumental role in the diagnostic pathway of many of these disorders, but the myriad of endocrinologic tests readily available to current clinicians may suggest their importance has lessened. We disagree. Recognition of these often subtle features can avoid the expense and psychological impact of an inappropriate diagnostic work-up, as well as expediting the diagnosis of potentially unsuspected disease. The metabolic and endocrine disorders discussed here are based on the distinctive changes produced around the hand and wrist.

Ultrasound for the diagnosis of gout-the value of gout lesions as defined by the Outcome Measures in Rheumatology ultrasound group

OBJECTIVE

To evaluate ultrasound for diagnosing gout using consensus-based Outcome Measures in Rheumatology ultrasound definitions of gout lesions.

METHODS

Ultrasound was performed in patients with clinically suspected gout. Joints (28) and tendons (26) were binarily evaluated for the Outcome Measures in Rheumatology gout lesions-double contour (DC), tophus, aggregates and erosions. Ultrasound assessment was compared with two reference standards: (i) presence of MSU crystals in joint/tophus aspirate (primary outcome) and (ii) ACR/EULAR 2015 gout classification criteria (secondary outcome). Both reference standards were evaluated by rheumatologists blinded to ultrasound findings. Sensitivity, specificity, accuracy, positive predictive value and negative predictive value of each ultrasound lesion against both reference standards were determined.

RESULTS

Eighty-two patients (70 men), mean age 62.4 (range 19-88) years, were included. Fifty-seven patients were MSU-positive whereas 25 patients were MSU-negative (no MSU crystals: 23; aspiration unsuccessful: 2). Of these 25 patients, three patients were classified as ACR/EULAR-positive (i.e. totally 60 ACR/EULAR-positive patients). All ultrasound lesions had high sensitivities for gout (0.77-0.95). DC and tophus showed high specificities (0.88-0.95), positive predictive values (0.94-0.98) and accuracies (0.82-0.84) when both reference standards were used. In contrast, low specificities were found for aggregates and erosions (0.32-0.59). Ultrasound of MTP joints for DC or tophus, knee joint for DC and peroneus tendons for tophus was sufficient to identify all MSU-positive patients with ultrasound signs of gout at any location.

CONCLUSION

Ultrasound-visualized DC and tophus, as defined by the Outcome Measures in Rheumatology ultrasound group, show high specificities, positive predictive values and accuracies for diagnosing gout and are therefore valid tools in clinical practice.

Diagnostic efficacy of joint ultrasonography, dual-energy computed tomography and minimally invasive arthroscopy on knee gouty arthritis, a comparative study

OBJECTIVE

This study aimed to investigate the diagnostic performance of minimally invasive arthroscopy for knee gout when comparing with joint ultrasonography and dual-energy computed tomography (DECT).

METHODS

From January 2016 to December 2018, 121 inpatients with knee joint swelling and pain were prospectively enrolled, including 63 gout patients and 58 non-gout patients. All patients underwent pre-operative ultrasonography and DECT to evaluate knee joint monosodium urate (MSU) deposits, followed by minimally invasive arthroscopy. The gold-standard for gout diagnosis was defined as the detection of MSU crystals in the synovial fluid under polarizing microscopic or pathological analysis.

RESULTS

The diagnostic results of ultrasonic double contour sign, hyperechogenic foci, MSU deposition (detected by DECT), MSU deposition (detected by arthroscopy) and MSU deposition in cartilage (detected by arthroscopy) were significantly associated with that of the gold-standard. Except for hyperechogenic foci, the other four indexes had high sensitivity and specificity (approximately or over 80%) and a large odds ratio (OR) (14.73 to 36.56), indicating good diagnostic performance. Detection of MSU deposition in cartilage by arthroscopy had a good diagnostic agreement with the ultrasonic double contour sign (κ = 0.711, p < 0.001).

CONCLUSION

Joint ultrasonography, DECT, and minimally invasive arthroscopy had high sensitivity and specificity for the diagnosis of knee gouty arthritis. Minimally invasive arthroscopy was superior to joint ultrasonography and DECT, which can be a useful supplement for the diagnosis of gout.

ADVANCES IN KNOWLEDGE

This is the first study comparing the diagnostic performance for knee gout among the joint ultrasonography, DECT, and minimally invasive arthroscopy.

The inflammatory role of silent urate crystal deposition in intercritical gout

OBJECTIVE

To study subclinical inflammation in intercritical gout patients and its relation to the estimated size of monosodium urate crystal deposition and cardiovascular risk factors.

METHODS

We performed a secretome analysis and the quantification of cytokine and adipokine plasma levels (IL-1β, IL-18, IL-6, sIL-6R, TNFα, CXCL5, RANTES, leptin, resistin and adiponectin) to analize subclinical inflammation in intercritical gout patients. Since it is currently not feasible to determinate the whole body deposit of monosodium urate crystals, we created an indirect clinical classification to estimate it. Then, we compared cytokine levels in controls and gout patients, and in patients with different crystal deposition size. We also studied the association between cytokine-levels and the number of cardiovascular risk factors.

RESULTS

Ninety consecutive patients attending a Crystal Arthritis Unit were studied. IL-18, sIL-6R, RANTES, leptin and adiponectin were higher in intercritical gout patients than in controls. An association was observed between IL-18, sIL6-R and RANTES levels and the size of crystal deposition. IL-18, sIL6-R, RANTES and leptin were higher in patients with no cardiovascular risk factors when compared with controls with no risk factors.

CONCLUSION

Our results showed that the levels of some proinflammatory cytokines and metabolic proteins are elevated in intercritical gout patients. The levels of certain cytokines was related to the estimated size of the monosodium urate crystal deposition and to the number of cardiovascular risk factors. These cytokine changes may help to explain the increase of the cardiovascular events in gout patients.

Performance of Ultrasound in the Clinical Evaluation of Gout and Hyperuricemia

Objective

To evaluate monosodium urate (MSU) crystal deposition and related lesions in the joints of patients with gout and hyperuricemia (HUA) using ultrasound. To explore the association between ultrasound findings and clinical features in gout and HUA.

Methods

A total of 202 patients with gout and 43 asymptomatic patients with HUA were included. The clinical data and ultrasonic assessment results were collected and statistically analyzed.

Results

Deposition of MSU crystals was found in 25.58% (11/43) of patients with asymptomatic HUA and 76.24% (154/202) of patients with gout. Of the 1,082 joints from patients with gout examined, 33.09% (358/1082) displayed MSU crystal deposition. In the joints with MSU crystal deposition, 77.37% (277/358) had a history of attacks. Among the joints of gouty arthritis, double contour sign (DCS), hyperechoic aggregate (HAG), and tophi were found in 32.65% (159/487), 7.80% (38/487), and 24.64% (120/487) of the joints, respectively. DCS and tophi, but not HAG, increasingly appeared with the extension of gout duration. In patients with more than 15 years of gout history, DCS, Tophi, and HAG were found in 48.18%, 40.00%, and 6.36% of US assessed joints, respectively. In patients with gout, synovial lesion and bone erosion were found in 17.74% (192/1082) and 7.58% (82/1082) of joints, respectively. The synovial lesion was related to HAG, while bone erosion was related to tophi and DCS. Nephrolithiasis was detected in 20.30% (41/202) of patients with gout and 4.65% (2/43) of HUA patients, indicating that nephrolithiasis occurred in more patients with gout than in patients with HUA.

Conclusion

HAG is an early performance of MSU crystal deposition in joints of gout and HUA. Both DCS and tophi are risk factors for bone erosion. Early urate-lowering therapy (ULT) should be considered in patients with gout, DCS, or tophi.

Synovial fluid analysis for the enhanced clinical diagnosis of crystal arthropathies in a tertiary care institution

INTRODUCTION/OBJECTIVES

Few studies have addressed the detection and clinical impact of different crystals in patients with diverse rheumatologic diagnoses in Latin America. The aim of this study was to assess the consistency between the clinical referring diagnosis and the identification of crystals, such as monosodium urate (MSU) and calcium pyrophosphate (CPP), in the synovial fluid (SF) of patients from a Mexican tertiary care institution.

METHODS

We reviewed the results of 264 SF analyses to identify any changes in diagnosis upon SF analysis. We reported patient medical file data on sex, age, diagnosis, and microscopic SF analysis results. We performed consistency analyses between referring diagnoses and SF findings with McNemar's test.

RESULTS

The prevalence of MSU crystals in SF was noted in 89.1% of gout cases and 9.09% of cases of calcium pyrophosphate disease (CPPD). CPP crystals were present in 54.5% of CPPD cases, 42.9% of osteoarthritis (OA) cases, and 7.27% of gout cases. Calcium hydroxyapatite (HA) crystals were identified in 5.45% of gout cases, 33.3% of rheumatoid arthritis (RA) cases, 57.1% of OA cases, and 63.6% of CPPD cases. Cholesterol and lipid crystals were present in small proportions in RA cases. Glucocorticoid crystals were observed in 1.85% of gout cases, 44.4% of RA cases, and 42.9% of OA cases. We observed an association of MSU identification with clinical suspicion of gout (P = 0.08), CPP with OA (P = 0.26) and CPPD (P = 0.50). An association was noted between HA and the diagnosis of CPPD (P = 0.84) and OA (P > 0.99). The number of initial diagnoses that changed upon SF analysis was 14.3%.

CONCLUSIONS

SF analysis has major diagnostic value regarding MSU crystals and gout. Our findings underscore the importance of SF crystal analysis in identifying the prevalence of crystals in the Mexican population. SF analysis provides for better diagnosis of crystal arthropathies and improves the quality of the medical care that the patient receives. Key Points • Synovial fluid analysis in laboratories from developing countries has been scarce. • In some cases, the initial diagnosis is modified after of synovial fluid analysis. • This study confirmed that synovial fluid analysis exhibits major diagnostic value for urate crystals and gout.

[Risk factors and diagnostic value for ultrasound-detected tendon monosodium urate crystal deposition in patients with gout]

OBJECTIVE

To evaluate frequency and patterns, risk factors of MSU (monosodium urate) crystal deposition at lower extremity tendon by ultrasonography in gout patients, and to explore diagnostic value by ultrasonography.

METHODS

Patients diagnosed with gout and age matched healthy controls had ultrasound scanning of both feet and knees including joints and tendons (achilles, quadriceps, and patellar tendon). Readers who scored the ultrasound scans for MSU crystal deposition were blinded to the patients' clinical diagnoses. Clinical characteristics were compared between positive and negative crystal deposition groups by US, and risk factors of MSU deposition in tendons were analyzed. Diagnostic values of MSU deposition were evaluated by ultrasonography according with positive MSU crystal in synovial fluid or tophi by polarized microscopy.

RESULTS

Eighty patients and eighty healthy controls were included. Thity-three patients (47.5%) had tophi by physical examination. The achilles tendon was the most commonly involved tendon site 41(51.2%), followed by the quadriceps tendons 22(27.5%), and patella tendon 10(12.5%). There were no MSU deposition in healthy control group at tendon by ultrasonography. Compared with negative MSU deposition at tendon site by ultrasonography, tendon MSU positive patients had longer mean gout duration [(87.3±40.9) months vs. (7.7±2.6) months, P=0.001];higher frequency of gout flare [2(1, 2) /year vs. 1(1, 1) /year, P=0.001]; higher BMI [(26.3±2.5) kg/m²vs. (23.3±2.1) kg/m², P=0.05]. Also, the mean serum uric acid and creatinine levels were higher in tendon MSU positive group [(584.6±87.6) μmol/L vs. (460.4±96.7) μmol/L, P=0.001] and [(90.9±33.3) μmol/L vs. (70.6±40.2) μmol/L, P=0.02] separately. Logistic regression analysis showed gout duration and flare frequency were independent risk factors for MSU deposition at tendon by ultrasonography (P < 0.01). Joint or tophi aspirations were performed in all the eighty gout patients, and positive MSU crystals in synovial fluid analysis by polarized microscopy were defined as the golden standard of gout diagnosis. When compared with the golden standard, the sensitivity and specificity were 94.0% and 78.0% separately for MSU deposition at tendon by ultrasonography.

CONCLUSION

Tendon involvement at the lower extremity tendons in gout is very common. Long gout disease duration and high frequency of gout flare are both independent risk factors of tendon MSU deposition by ultrasonography. Ultrasonography had good sensitivity and specificity for detecting tendinous tophi and aggregates.

Imaging of Joints and Bones in Autoinflammation

Autoinflammatory disorders are commonly characterized by seemingly unprovoked systemic inflammation mainly driven by cells and cytokines of the innate immune system. In many disorders on this spectrum, joint and bone involvement may be observed and imaging of these manifestations can provide essential diagnostic information. This review aimed to provide a comprehensive overview of the imaging characteristics for major diseases and disease groups on the autoinflammatory spectrum, including familial Mediterranean fever (FMF), Behçet disease (BD), crystal deposition diseases (including gout), adult-onset Still's disease (AoSD), and syndromatic synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO)/chronic recurrent multifocal osteomyelitis (CRMO). Herein, we discuss common and distinguishing imaging characteristics, phenotypical overlaps with related diseases, and promising fields of future research.

External validation of Gout-calculator performance on a cohort of acute arthritis (SYNOLACTATE) sparing distal joints such as hallux and midfoot. A cross-sectional study of 170 patients

OBJECTIVE

To evaluate the performance of the Gout-calculator in a cohort of consecutive acute arthritis affecting large and intermediate joints (without an attack on hallux or midfoot joints).

METHODS

A retrospective study. Gout-calculator data were collected in medical records of patients included in the prospective consecutive cohort of acute arthritis called SYNOLACTATE. The diagnosis of gout was defined by the presence of sodium urate crystals in synovial fluid. The diagnostic performance of the Gout-calculator was studied by performing an ROC curve with the calculation of its AUC (95% CI) as well as the calculation of Sensitivity (Se), Specificity (Sp), and positive likelihood ratio (LR+).

RESULTS

170 patients with acute arthritis were included. Variables associated with the diagnosis of gout were as follows: serum uric acid > 350 μmol/L (OR 5.52 (2.52-12.1), p < 0.001), joint redness (OR 5.08 (1.85-14.0), p = 0.001), previous patient-reported arthritis attack (OR 4.04 (1.92-8.49), p < 0.001), male (OR 3.00 (1.17-7.69), p = 0.02), hypertension or cardiovascular disease (OR 2.33 (1.07-5.06), p = 0.03). The median (IQR) of Gout-calculator was significantly higher in gouty arthritis (7.0 [5.5-8.1]) than in associated-CPP acute arthritis (4.0 [2.0-5.8]), septic arthritis (3.0 [2.0-5.1]), or others arthritis (3.5 [2.0-5.5]). The AUC was 0.833 (0.768-0.897) with for the threshold ≥ 8, a Se at 27.5% (0.161-0.428), Sp 97.7% (0.934-0.992), and LR+ 11.9 (3.5-40).

CONCLUSION

Despite diagnostic performances close to those published, the use of the Gout-calculator is not sufficient for the diagnosis of gout or to exclude the differential diagnosis of septic arthritis in the SYNOLACTATE cohort.

KEY POINTS

• For a Gout-calculator threshold of ≤ 4, Sensitivity is 92.5%, Specificity 50.8% and LR- 0.15 to the gout diagnosis. • For a Gout-calculator threshold of > = 8, Sensitivity is 27.5%, Specificity 97.7% and LR+ 11.9 to the gout diagnosis. • In a population of acute arthritis affecting large joints, Gout-calculator is not sufficient to discriminate between gouty arthritis and septic arthritis.

Imaging of crystalline arthropathy in 2020

Crystal-related arthropathies are the result of crystal deposition in joint and periarticular soft tissues. Identification of urate crystals is mandatory to distinguish gout from other crystalline arthropathies, including calcium pyrophosphate dihydrate and basic calcium phosphate crystal deposition diseases. ACR/EULAR classification criteria for gout included dual-energy computed tomography and ultrasound with equal impact to the final score. Different diagnostic strengths of these imaging modalities depend on disease duration and scanned anatomic site. While ultrasound has been indicated as the first-choice imaging technique, especially in the early stages of the disease, dual-energy computed tomography has shown to be highly specific, allowing the detection of crystal deposits in anatomic sites not accessible by ultrasound, such as the spine. At the spinal level, MRI findings are usually nonspecific. Finally, there is preliminary evidence that at the knee, dual-energy computed tomography may discriminate calcium pyrophosphate dihydrate from basic calcium phosphate crystal deposits.

An update on gout diagnosis and management for the primary care provider

Gout is the most common inflammatory arthritis in the US, affecting 3.9% of the population. Although many effective gout therapies are available for acute flares and chronic management, it is suboptimally treated worldwide, and recurrent gout flares can cause significant pain and irreversible joint damage.

UltraSound evaluation in follow-up of urate-lowering therapy in gout phase 2 (USEFUL-2): Duration of flare prophylaxis

OBJECTIVES

To determine whether changes in ultrasonography (US) features of monosodium urate crystal deposition is associated with the number of gouty flares after stopping gout flare prophylaxis.

METHODS

We performed a 1-year multicentre prospective study including patients with proven gout and US features of gout. The first phase of the study was a 6-month US follow-up after starting urate-lowering therapy (ULT) with gout flare prophylaxis. After 6 months of ULT, gout flare prophylaxis was stopped, followed by a clinical follow-up (M6 to 12) and ULT was maintained. Outcomes were the proportion of relapsing patients between M6 and M12 according to changes of US features of gout and determining a threshold decrease in tophus size according to the probability of relapse.

RESULTS

We included 79 gouty patients [mean (±SD) age 61.8±14 years, 91% males, median disease duration 4 (IQR 1.5;10) years]. Among the 49 completers at M12, 23 (47%) experienced relapse. Decrease in tophus size ≥50% at M6 was more frequent without than with relapse (54% vs. 26%, P=0.049). On ROC curve analysis, a threshold decrease of 50.8% in tophus size had the best sensitivity/specificity ratio to predict relapse [AUC 0.649 (95% confidence interval 0.488; 0.809)]. Probability of relapse was increased for patients with a decrease in tophus size <50% between M0 and M6 [OR 3.35 (95% confidence interval 0.98; 11.44)].

CONCLUSION

A high reduction in US tophus size is associated with lower probability of relapse after stopping gout prophylaxis. US follow-up may be useful for managing ULT and gout flare prophylaxis.

The pattern of allopurinol prescription in a university hospital practice

Background

Allopurinol as a drug is commonly used to treat gout and its complications. The aim usually is to lower the level of serum uric acid. Also, it was found to be prescribed in cases of asymptomatic hyperuricemia. However, this medication has serious side effects and some of these are fatal. So the aim of the current research work is to look at its use, whether properly indicated or not, in a university hospital.

Results

A total of 427 patients were included in this study. Only 3.7% (16) of the patients had the drug for significant hyperuricemia. Gout was confirmed in 40 (9.4%) patients.

Conclusion

It is clear that most patients received allopurinol without proper indications. The inappropriate use of allopurinol should be looked at to reduce the cost of medication and more importantly to avoid possible adverse effects.

Gout of ankle and foot: DECT versus US for crystal detection

OBJECTIVE

To compare dual-energy computed tomography (DECT) and ultrasound (US) in detecting monosodium urate (MSU) crystals in the ankle and foot in patients with acute gouty arthritis.

METHODS

Bilateral ankle and foot were examined by DECT and US and the differences between the findings were compared.

RESULTS

A total of 50 patients underwent DECT and US examinations. At the patient level, the overall positivity of crystal deposition detected by DECT was higher than that by US (92% vs 68%, P = 0.005). The agreement of detecting crystal deposition between DECT and US was not very strong (К = 0.44, P = 0.003). At different joint/area levels, there were significant differences between the two examinations in the area of the dorsum (36% vs 12%, P = 0.009) and metatarsal bone (34% vs 12%, P = 0.017), but the sensitivity of DECT and US was similar in the first metatarsophalangeal joint (MTP) and ankle areas (P>0.05). Agreement between the two examinations in the ankle and first MTP was very strong (К = 0.86, P < 0.001; К = 0.79, P < 0.001, respectively). However, agreement between the two examinations in other joints/areas was poor.

CONCLUSION

These findings indicated that DECT should be the first choice for acute gouty arthritis in patients with ankle and foot involvement. Key Points • There is little data regarding DECT and US in detecting MSU crystals in the ankle and foot in patients with acute gouty arthritis. • The overall positivity of crystal deposition detected by DECT was higher than that by US, but the sensitivity of DECT and US was similar in the first metatarsophalangeal joint (MTP) and ankle areas. • Agreement between the two examinations in the ankle and first MTP was very strong; however, agreement between the two examinations in other joints/areas was poor.

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.