Advanced Imaging of Gout and Other Inflammatory Diseases Around the Knee.

The knee is one of the most commonly affected joints in the course of inflammatory arthropathies, such as crystal-induced and autoimmune inflammatory arthritis. The latter group includes systemic connective tissue diseases and spondyloarthropathies. The different pathogenesis of these entities results in their varied radiologic images. Some lead quickly to joint destruction, others only after many years, and in the remaining, destruction will not be a distinguishing radiologic feature.Radiography, ultrasonography, and magnetic resonance imaging have traditionally been the primary modalities in the diagnosis of noninflammatory and inflammatory arthropathies. In the case of crystallopathies, dual-energy computed tomography has been introduced. Hybrid techniques also offer new diagnostic opportunities. In this article, we discuss the pathologic findings and imaging correlations for crystallopathies and inflammatory diseases of the knee, with an emphasis on recent advances in their imaging diagnosis.

2023 EULAR recommendations on imaging in diagnosis and management of crystal-induced arthropathies in clinical practice.

OBJECTIVE: To formulate evidence-based recommendations and overarching principles on the use of imaging in the clinical management of crystal-induced arthropathies (CiAs). METHODS: An international task force of 25 rheumatologists, radiologists, methodologists, healthcare professionals and patient research partners from 11 countries was formed according to the EULAR standard operating procedures. Fourteen key questions on the role of imaging in the most common forms of CiA were generated. The CiA assessed included gout, calcium pyrophosphate deposition disease and basic calcium phosphate deposition disease. Imaging modalities included conventional radiography, ultrasound, CT and MRI. Experts applied research evidence obtained from four systematic literature reviews using MEDLINE, EMBASE and CENTRAL. Task force members provided level of agreement (LoA) anonymously by using a Numerical Rating Scale from 0 to 10. RESULTS: Five overarching principles and 10 recommendations were developed encompassing the role of imaging in various aspects of patient management: making a diagnosis of CiA, monitoring inflammation and damage, predicting outcome, response to treatment, guided interventions and patient education. Overall, the LoA for the recommendations was high (8.46-9.92). CONCLUSIONS: These are the first recommendations that encompass the major forms of CiA and guide the use of common imaging modalities in this disease group in clinical practice.

False-Positive Metastatic Bone Disease on FDG PET/CT Due to Multilevel Tophaceous Gout of the Spine.

ABSTRACT: A 74-year-old woman was referred for 18 F-FDG PET/CT for the evaluation of incidental CT finding of expansile destruction of left L4/5 facet joint with associated soft tissue mass concerning for a metastatic deposit. The FDG PET/CT revealed variable abnormally increased FDG activity involving multiple facet joints in all regions of the spine with corresponding expansile "punched-out" lytic lesions with sclerotic rims and overhanging margins on CT, raising the possibility of inflammatory polyarthropathy, including gout, as a differential diagnosis. Dual-energy CT of lumbar spine and CT-guided biopsy and culture of the left L4/5 facet joint demonstrated the presence of urate crystal deposition with no evidence of malignancy or infection, confirming the diagnosis of multilevel tophaceous gout of the spine.

Increased frequency of hepatic steatosis and fibrosis in patients with gout detected by transient elastography.

OBJECTIVES: It has been suggested that gout is associated with non-alcoholic fatty liver disease (NAFLD). Our aim was to assess NAFLD in gout patients using the validated non-invasive imaging technique, transient elastography (FibroScan). METHODS: FibroScans in consecutive gout patients in a single centre from 11/1/2016 to 11/1/2021 and reviewed retrospectively. FibroScan results include the E- score (kPA), measuring liver stiffness, and controlled attenuation parameter (CAP) score (dB/m), assessing steatosis. In addition, a FIB-4 fibrosis score was calculated. RESULTS: 47 gout patients (7 females, 14.9%; 40 males, 85.1%) underwent FibroScans. The mean age was 59.8 years, the mean body mass index (BMI) was 30.95 kg/m2, and gout duration 0-49 years. Tophi were present in 11 (26.2%). Comorbidities included dyslipidaemia (86.7%), diabetes mellitus (31.1%), known liver disease (33.3%), current alcohol consumption (46.8%), ALT or AST elevations (54.4%), and hyperuricaemia (53.7%). FibroScan results revealed hepatic steatosis (CAP >238 dB/m) in 40 (85.1%) and were significantly associated with BMI (r=0.53, p=0.0001) but not age, serum urate (SU), glucose, triglycerides, ALT, AST. FibroScan also revealed fibrosis (E score >7) in 9 (19.1%); severe fibrosis (cirrhosis) in 8. Fibrosis was significantly associated with age (p=0.03) and known liver disease (p=0.003) but not BMI, SU, or comorbidities. The FIB-4 score was significantly associated with the fibrosis score (r2=0.24, p=0.0009) but not with CAP, ALT, or AST. CONCLUSIONS: Despite not being associated with common gout comorbidities, fatty liver and liver fibrosis were common in this gout cohort, suggesting FibroScan screening in gout patients to assess NAFLD, irrespective of serum transaminase levels.

The prevalence and independent risk factors of elevated common carotid artery intima-media thickness and carotid plaque in patients with gout.

OBJECTIVES: Gout patients are at high risk of carotid atherosclerosis, which could be convincingly reflected by common carotid artery intima-media thickness (CCAIMT) and carotid plaque. The current study aimed to investigate the prevalence and risk factors of thick CCAIMT and carotid plaque in gout patients. METHODS: Comprehensive demographic characteristics, chronic comorbidities, disease features, and biochemical indexes (42 parameters) were obtained from 237 gout patients. CCAIMT and carotid plaque were evaluated by bilateral carotid artery ultrasound in gout patients and 80 healthy controls. RESULTS: The CCAIMT and carotid plaque percentage were increased in gout patients compared to healthy controls (both p<0.001). In detail, the prevalence of thick CCAIMT (>0.9 mm) and carotid plaque was 22.4% and 34.6% in gout patients, respectively. Forward-stepwise multivariate logistic regression model revealed that age (p<0.001, odds ratio (OR)=1.143], disease duration (p=0.001, OR=1.176), alkaline phosphatase (ALP) (p=0.002, OR=1.037), and low-density lipoprotein cholesterol (LDLC) (p=0.039, OR=2.144) were independently associated with elevated thick CCAIMT risk, while serum uric acid (SUA) (p=0.002, OR=0.992) exhibited an opposite trend; their combination well-identified thick CCAIMT risk [area under the curve (AUC)=0.910] by receiver operator characteristic (ROC) curve. Meanwhile, age (p<0001, OR=1.116), tophus (p=0.009, OR=3.523), and triglycerides (TG) (p=0.014, OR=1.323) were independently associated with a higher risk of carotid plaque, while SUA (p=0.008, OR=0.995) showed an opposite trend; their combination also well-identified carotid plaque risk (AUC=0.886) by ROC curve. CONCLUSIONS: Thick CCAIMT and carotid plaque are prevalent in gout patients, whose occurrence relates to age, disease duration, ALP, LDLC, SUA, TG, and tophus.

Gout-Induced Cervical Deformity and Progressive Myelopathy Mimicking Infection Requiring Cervical Reconstruction.

BACKGROUND: This study describes a rare case where gout, a condition primarily associated with joint inflammation, initially manifested as a progressive cervical kyphotic deformity, mimicking infection and causing myelopathy. The patient, a previously healthy 56-year-old woman, presented with severe jaw pain and a temporomandibular joint abscess, alongside 2 months of worsening balance and arm/hand tingling. Extensive clinical and radiographic assessments revealed a severe cervical kyphotic deformity with bony erosion at multiple vertebral levels, raising suspicion of an infectious cause of compressive myelopathy. METHODS: The patient underwent an urgent staged surgical intervention involving multilevel cervical decompression and fusion, coupled with cervical deformity correction. RESULTS: Post surgery, she received antibiotics for 7 days, during which pathologic analysis unveiled collections of macrophages reacting to urate crystal deposition in a pattern consistent with gouty tophus. This unexpected diagnosis marked a novel case of undiagnosed gout-induced severe cervical deformity presenting with myelopathic symptoms and successfully managed through cervical spine deformity correction. CONCLUSIONS: This report underscores the significance of considering gout as a potential cause when encountering unusual spinal pathologies, especially in cases where gout-related symptoms are atypical. The presented 540-degree surgical approach effectively addressed both the cervical deformity and gout-induced myelopathic symptoms. To the best of our knowledge, this study represents the first documented instance of a patient with undiagnosed gout-induced severe cervical deformity successfully treated through cervical spine deformity correction, emphasizing the importance of vigilance and innovative management approaches in such rare clinical scenarios. As of the 2-year follow-up, the patient exhibited significant symptom improvement and overall well-being.

The Role of Ultrasound Semi-Quantitative Scoring in the Diagnosis and Assessment of Gout and Hyperuricemia.

OBJECTIVES: To develop an ultrasound semi-quantitative scoring system for the diagnosis and evaluation of gout and hyperuricemia. METHODS: This study included 348 male patients: 81 patients with asymptomatic hyperuricemia, 182 patients with gout, and 85 patients with other arthritis. Clinical data were collected, ultrasound was detected, gout activity score was calculated to assess disease activity, and statistical analysis was performed. RESULTS: Monosodium urate crystal deposition and subclinical arthritis were detected in 17 patients with asymptomatic hyperuricemia, with lesions concentrated in the metatarsophalangeal joint, ankle and peroneus-longus and brevis at rate of 91.8%. Gout was significantly higher than non-gouty arthritis in crystal scores (sum scores of double contour, aggregates, and tophi), but not in inflammation scores (sum scores of synovial hypertrophy, power Doppler [PD] activity, and tenosynovitis) and bone erosion. The optimal cut-off score for the diagnosis of gout by the crystal score was 2. The sensitivity, specificity, and AUC were 95.4%, 97.1%, and .965, respectively. Gout flare had higher inflammation scores than intercritical gout, while bone erosion scores were lower than intercritical gout. The active gout patients had higher ultrasound scores of tophi, bone erosion, and PD activity than the remission group (P < .001). The sensitivity, specificity and area under the receiver operating characteristic curve (AUC) for the identification with high disease activity gout by ultrasound semi-quantitative composite score were 76.2%, 84.2%, and .812, respectively. CONCLUSION: Ultrasound helps early identification of patients at risk in asymptomatic hyperuricemia. Ultrasound semi-quantitative scoring allows for more objective and accurate assessment of gout lesions, correlates with disease activity, and helps in the diagnosis and assessment of gout.

Factors influencing the kinetics of MSU crystal depletion measured with dual-energy CT in patients with gout.

OBJECTIVE: To examine factors influencing the kinetics of monosodium urate (MSU) crystal dissolution measured with dual-energy computed tomography (DECT) during follow-up of patients with gout. METHODS: Patients with a diagnosis of gout with baseline knees and feet DECT scans exhibiting MSU crystal volumes ≥0.1 cm3 and at least one follow-up DECT were included. Spearman's correlation coefficient was used to search for association between change from baseline MSU crystal volume at 6, 12, 18 and 24 months and serum urate (SU) level. Associations between percentage change from the baseline volume of MSU crystal deposits and explanatory variables were assessed using linear mixed models. RESULTS: Sixty-two patients (age 67.3±12.8 years; 53 (85%) males) cumulating 104 follow-up DECT scans were included. Overall, SU target levels (<6.0 and <5.0 mg/dL) were achieved by 48 (77%) and 36 (58%) patients, respectively. There was a good correlation (r=0.66; p<0.0001) observed between SU level and percentage change in MSU crystal volume. The median decrease from baseline MSU crystal volume was greater in patients reaching the <5.0 mg/dL SU target than in those reaching ≥5.0 SU <6.0 mg/dL: -85% (95% CI: -94% to -72%) versus -40% (-57% to -22%; p<0.05) at 12 months. In multivariable analysis, time (in days) with a multilevel coefficient of -0.06 (95% CI: -0.08 to -0.03, p<0.001), hypertension (coefficient: 41.87, 95% CI: 16.38 to 67.18, p<0.01) and SU level <5.0 mg/dL (coefficient: -39.46, 95% CI: -70.93 to -8.34, p=0.02) were the only variables significantly associated with MSU crystal volume change. CONCLUSION: In patients with DECT-measured MSU crystal deposition, reaching the <5.0 mg/dL SU target provides more extensive and rapid crystal dissolution than reaching the <6.0 mg/dL SU target.

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.

The statistical challenge of analysing changes in dual energy computed tomography (DECT) urate volumes in people with gout.

BACKGROUND: Dual energy computed tomography (DECT) allows direct visualization of monosodium urate crystal deposition in gout. However, DECT urate volume data are often highly skewed (mostly small volumes with the remainder considerably larger), making statistical analyses challenging in longitudinal research. The aim of this study was to explore the ability of various analysis methods to normalise DECT urate volume data and determine change in DECT urate volumes over time. METHODS: Simulated datasets containing baseline and year 1 DECT urate volumes for 100 people with gout were created from two randomised controlled trials. Five methods were used to transform the DECT urate volume data prior to analysis: log-transformation, Box-Cox transformation, log(X-(min(X)-1)) transformation; inverse hyperbolic sine transformation, and rank order. Linear regression analyses were undertaken to determine the change in DECT urate volume between baseline and year 1. Cohen's d were calculated as a measure of effect size for each data treatment method. These analyses were then tested in a validation clinical trial dataset containing baseline and year 1 DECT urate volumes from 91 people with gout. RESULTS: No data treatment method successfully normalised the distribution of DECT urate volumes. For both simulated and validation data sets, significant reductions in DECT urate volumes were observed between baseline and Year 1 across all data treatment methods and there were no significant differences in Cohen's d effect sizes. CONCLUSIONS: Normalising highly skewed DECT urate volume data is challenging. Adopting commonly used transformation techniques may not significantly improve the ability to determine differences in measures of central tendency when comparing the change in DECT urate volumes over time.

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.

Association between specific ultrasound features of joints and impaired kidney function among gout patients.

OBJECTIVE: To investigate the relationship between the specific ultrasonic manifestations of lower limb joints and impaired kidney function in gouty arthritis. METHODS: In this cross-sectional study, 408 patients with gouty arthritis were divided into two groups based on the status of renal function: normal group (n = 240) and renal impairment (n = 168) group. All patients underwent ultrasound examination of the bilateral knee, ankle, and first metatarsophalangeal joints to detect ultrasound features of double-contour sign (DC) and tophus. Multiple logistic regression analysis was conducted to assess the association between kidney dysfunction and ultrasound features. A number of potential clinical confounders were adjusted in the model. RESULTS: Univariable conditional logistic regression produces several significant risk factors of impaired kidney function which were the highest and current lever of serum urate acid, course of disease, frequency of attack, hyperlipidemia, hypertension, diabetes, coronary heart disease, presence of multiple tophus, and DC (P < 0.05). After correcting the course of disease and other risk factors, tophus was still an independent risk factor of impaired kidney function and the multivariable adjusted odds ratios (95% CI) was 1.789 (1.005-3.185, P = 0.05), however, the association was not significant in DC (OR = 1.098, 95% CI: 0.668-1.803, P = 0.71). CONCLUSION: The ultrasound feature of tophus was associated with kidney dysfunction in patients with gout, independent of clinical risk factors, which may be helpful in guiding clinical practice.

Identification of tophi in ultrasound imaging based on transfer learning and clinical practice.

Gout is a common metabolic disorder characterized by deposits of monosodium urate monohydrate crystals (tophi) in soft tissue, triggering intense and acute arthritis with intolerable pain as well as articular and periarticular inflammation. Tophi can also promote chronic inflammatory and erosive arthritis. 2015 ACR/EULAR Gout Classification criteria include clinical, laboratory, and imaging findings, where cases of gout are indicated by a threshold score of ≥ 8. Some imaging-related findings, such as a double contour sign in ultrasound, urate in dual-energy computed tomography, or radiographic gout-related erosion, generate a score of up to 4. Clearly, the diagnosis of gout is largely assisted by imaging findings; however, dual-energy computed tomography is expensive and exposes the patient to high levels of radiation. Although musculoskeletal ultrasound is non-invasive and inexpensive, the reliability of the results depends on expert experience. In the current study, we applied transfer learning to train a convolutional neural network for the identification of tophi in ultrasound images. The accuracy of predictions varied with the convolutional neural network model, as follows: InceptionV3 (0.871 ± 0.020), ResNet101 (0.913 ± 0.015), and VGG19 (0.918 ± 0.020). The sensitivity was as follows: InceptionV3 (0.507 ± 0.060), ResNet101 (0.680 ± 0.056), and VGG19 (0.747 ± 0.056). The precision was as follows: InceptionV3 (0.767 ± 0.091), ResNet101 (0.863 ± 0.098), and VGG19 (0.825 ± 0.062). Our results demonstrate that it is possible to retrain deep convolutional neural networks to identify the patterns of tophi in ultrasound images with a high degree of accuracy.

Changes in the structure and function of the left ventricle in patients with gout: A study based on three-dimensional speckle tracking echocardiography.

PURPOSE: Studies have shown that gout can increase the risk of cardiovascular disease. Three-dimensional speckle-tracking echocardiography (3D-STE), a sensitive imaging technology, enables the detection of subtle myocardial dysfunctions. Our aim is to evaluate the left ventricular (LV) functions in patients with gout using 3D-STE. METHODS: 80 subjects: 40 with gout and 40 as normal controls were involved. We obtained and analyzed these parameters from the dynamic images of a 3D full-volume dataset: global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain (GRS), Twist, 16-segmental time-to-peak longitudinal strain (TTP) and systolic dyssynchrony index (SDI)besides other relevant parameters. RESULTS: Compared with the normal group, gout patients were more likely to have left ventricular remodeling. The patients with gout showed decreased Em, increased E/Em and larger volume index of the left atrium (LAVI) indicating reduced diastolic function. The peak GLS (-17.42 ± 2.02 vs. -22.40 ± 2.57, P < 0.001), GCS (-27.04 ± 3.75 vs. -34.85 ± 4.99, P < 0.001), GRS (38.22 ± 4.28 vs. 46.15 ± 5.17, P < 0.001), and Twist (15.18 ± 5.45 vs. 19.02 ± 5.29, P = 0.015) were significantly lower in patients with gout than in healthy participants. The SDI (5.57 ± 1.46 vs. 4.91 ± 1.19, P = 0.016) was significantly increased in patients with gout compared with normal controls. There was no significant between-group difference in TTP (P = 0.43). The systolic GLS, GRS and GCS peak values increased gradually from the base to the apex, with the lowest values in the basal segment in patients with gout. Receiver-operating characteristic curve analysis revealed among these strains GLS has the largest area under the curve (AUC: 0.93, P < 0.001), the cutoff value of -18.97% with a sensitivity and specificity of 80.0% and 92.0%, respectively, for differentiating two groups. A multivariate linear regression analysis shows that the relationship between gout and strain parameters including GLS, GRS, and GCS is statistically significant (P < 0.001). CONCLUSION: Although patients with gout having a normal ejection fraction, structural remodeling of the left ventricle and subclinical LV deformation may occur. 3D-STE can detect subtle cardiac dysfunctions in patients with gout at an early stage.