Imaging in gout: insights into the pathological features of disease

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.

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.

Xanthoma Combined With Gout Infiltration of the Achilles Tendon: A Case Report

Xanthoma is a rare condition mostly caused by hyperlipidemia. The pathogenesis of gout is hyperuricemia, which is caused by a disorder of purine metabolism and/or a decrease in uric acid excretion. Xanthoma combined with gout is very rare. This case report presents magnetic resonance images of a case of xanthoma combined with gout infiltration of the Achilles tendon.

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.

Gout mimicking spondyloarthritis: case report and literature review

Gout is clinically characterized by episodes of monoarthritis, which not only typically affects the peripheral joints but also occasionally affect the axial joint, such as the sacroiliac joint (SIJ), and often mimics spondyloarthritis (SpA). Two cases of gout mimicking SpA are presented in the current paper. One patient was a 32-year-old man with a history of asymmetrical oligoarthritis of ankle and metatarsophalangeal joints (MTPJ). He had left gluteal pain for 2 weeks. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed the bone erosion of the left SIJ. T1-weighted MRI showed hypointense T1 and hyperintense T2 signals of the left SIJ. The other patient was a 24-year-old man with left back pain and hip pain for 4 months and intermittent fever for 3 months. He had a history of gout for 3 years. Both patients underwent CT-guided sacroiliac biopsy, and monosodium urate (MSU) crystals were shown by polarized microscopy. Gout can often mimic SpA and seldomly affects the SIJ. Thus, its correct diagnosis and adequate therapy can halt the development of such damaging complications.

Gout: an Asia-Pacific update

Even though, Hippocrates recognized gout as an affection of older men and a product of high living long back in 5th century BC, this painful condition promises to accompany humanity to the 21st century. The incidence is progressively rising and females are also affected in the modern era. There are also regional and ethnic variations in the incidence, the genetics of which is being studied. The recommended best therapy for the acute attacks and long term prophylaxis has improved remarkably in the recent years. However, patients are often treated inadequately and risk factors for their disease are not well explored in daily practice. Although well designed long term studies of current and newer treatment are welcomed, educating doctors especially the primary care physicians who manage majority of gout cases, in optimizing the currently available management options would improve the present care.

International Consensus for ultrasound lesions in gout: results of Delphi process and web-reliability exercise

OBJECTIVE

To produce consensus-based definitions of the US elementary lesions in gout and to test their reliability in a web-based exercise.

METHODS

The process consisted of two steps. In the first step a written Delphi questionnaire was developed from a systematic literature review and expert international consensus. This collated information resulted in four statements defining US elementary lesions: double contour (DC), tophus, aggregates and erosion. The Delphi questionnaire was sent to 35 rheumatology experts in US, asking them to rate their level of agreement or disagreement with each statement. The second step tested the reliability by a web-exercise. US images of both normal and gouty elementary lesions were collected by the participants. A facilitator then constructed an electronic database of 110 images. The database was sent to the participants, who evaluated the presence/absence of US elementary lesions. A group of 20 images was displayed twice to evaluate intra-reader reliability.

RESULTS

A total of 32 participants responded to the questionnaires. Good agreement (>80%) was obtained for US definitions on DC, tophus, aggregates and erosion in the Delphi exercise after three rounds. The reliability on images showed inter-reader κ values for DC, tophus, aggregates, erosion findings of 0.98, 0.71, 0.54 and 0.85, respectively. The mean intra-reader κ values were also acceptable: 0.93, 0.78, 0.65 and 0.78, respectively.

CONCLUSION

This, the first consensus-based US definition of elementary lesions in gout, demonstrated good reliability overall. It constitutes an essential step in developing a core outcome measurement that permits a higher degree of homogeneity and comparability between multicentre studies.

Spinal and sacroiliac gouty arthritis: report of a case and review of the literature

In this case report, we describe an "uncommon" case of axial gouty arthropathy in a 69-year-old woman with bilateral sciatica that was thoroughly evaluated with conventional radiography, CT scan, magnetic resonance imaging, bone scintigraphy, and PET-CT. Axial gouty arthropathy should be included in the differential diagnosis of chronic low back pain, mainly when several risk factors for gout are present.

Systemic staging for urate crystal deposits with dual-energy CT and ultrasound in patients with suspected gout

Objective of the study is to compare the diagnostic accuracy for detecting monosodium urate crystal deposits between dual-energy CT (DECT) and ultrasound (US). Sixty consecutive patients (49 men, mean age 62 years) with clinically suspected gout were included in this case-control study. DECT and US of feet, knees, hands and elbows were performed in all patients. Polarisation microscopy of synovial fluid or a score incorporating serum uric acid level, first MTP joint involvement, gender, previous patient-reported arthritis attack, cardiovascular diseases, joint redness and onset within 1 day was used as standard of reference. Standard of reference classified 39 patients as gout positive. Sixteen patients had gout and a concomitant rheumatic disease. Sensitivities for diagnosis of gout disease were 84.6 % (33/39) for DECT and 100 % (39/39) for US. Specificities were 85.7 % (18/21) for DECT and 76.2 % (16/21) for US. Positive and negative predictive values were 91.7 % (33/36) and 75.0 % (18/24) for DECT, 88.6 % (39/44) and 100 % (16/16) for US, respectively. Urate crystals were detected most frequently in MTP1 joints (DECT 20/78, US 58/78), any other toe joints (DECT 25/78, US 62/78) and knees (DECT 41/78, US 31/78). The volumetry of DECT computed a mean urate crystal deposit load of 2.1 cm(3) (SD 9.6 cm(3)). A mean effective dose of ≤0.5 mSv was estimated. DECT is more specific for the diagnosis of gout than US. However, it fails to detect small urate crystal deposits. It might be particularly useful for patients with ambivalent findings, concomitant rheumatic diseases and with non-conclusive joint aspiration.

The structural consequences of calcium crystal deposition

Calcium pyrophosphate dihydrate and basic calcium phosphate (BCP) crystals are the most common calcium-containing crystals associated with rheumatic disease. Clinical manifestations of calcium crystal deposition include acute or chronic inflammatory and degenerative arthritides and certain forms of periarthritis. The intra-articular presence of BCP crystals correlates with the degree of radiographic degeneration. Calcium crystal deposition contributes directly to joint degeneration. Vascular calcification is caused by the deposition of calcium hydroxyapatite crystals in the arterial intima. These deposits may contribute to local inflammation and promote further calcification, thus aggravating the atherosclerotic process. Calcium crystal deposition results in substantial structural consequence in humans.

Arthritis mimicking sports-related injuries

Arthritis, including inflammatory, crystal deposition, and synovial proliferative disorders, may mimic sports injury. The purpose of this article is to review the clinical and radiologic findings of arthropathies that can present in athletes and be confused with internal derangement.