Is Active Synovitis of Metacarpophalangeal Joints a Neuropathic Condition in Rheumatoid Arthritis Patients? Results from an Ultrasound Study of Palmar Digital Nerves.

(1) Background: Rheumatoid arthritis (RA) is a chronic inflammatory joint disease, primarily characterized by pain. A significant proportion of patients report symptoms suggestive of neuropathic pain. The objectives of this study were to investigate the presence of an increased cross-sectional area (CSA) of the palmar digital nerves by ultrasound in patients with active synovitis of the metacarpophalangeal joints and to identify potential predictors of such an increase. (2) Methods: An ultrasound examination of the clinically most affected hand (from the second to the fifth metacarpophalangeal joint) was performed. The presence of synovitis was scored using a 0-3 semiquantitative method for each joint. The CSA of each pair of palmar digital nerves was measured. (3) Results: A significant correlation was found between the sum of the CSAs of the nerves and the Clinical Disease Activity Index (CDAI) (r = 0.387), as well as with the ultrasonographic grading of synovitis (r = 0.381) both at the patient and the joint level. These two variables, aimed at measuring disease activity, along with male gender, are the only predictors of the CSA of the palmar digital nerves. (4) Conclusions: Synovial inflammation of the metacarpophalangeal joints is, therefore, a condition that can influence the CSA of the palmar digital nerves and may partially explain neuropathic pain in patients with RA.

Power Doppler signal at the enthesis and bone erosions are the most discriminative OMERACT ultrasound lesions for SpA: results from the DEUS (Defining Enthesitis on Ultrasound in Spondyloarthritis) multicentre study.

OBJECTIVES: To assess, in spondyloarthritis (SpA), the discriminative value of the Outcome Measures in Rheumatology (OMERACT) ultrasound lesions of enthesitis and their associations with clinical features in this population. METHODS: In this multicentre study involving 20 rheumatology centres, clinical and ultrasound examinations of the lower limb large entheses were performed in 413 patients with SpA (axial SpA and psoriatic arthritis) and 282 disease controls (osteoarthritis and fibromyalgia). 'Active enthesitis' was defined as (1) power Doppler (PD) at the enthesis grade ≥1 plus entheseal thickening and/or hypoechoic areas, or (2) PD grade >1 (independent of the presence of entheseal thickening and/or hypoechoic areas). RESULTS: In the univariate analysis, all OMERACT lesions except enthesophytes/calcifications showed a significant association with SpA. PD (OR=8.77, 95% CI 4.40 to 19.20, p<0.001) and bone erosions (OR=4.75, 95% CI 2.43 to 10.10, p<0.001) retained this association in the multivariate analysis. Among the lower limb entheses, only the Achilles tendon was significantly associated with SpA (OR=1.93, 95% CI 1.30 to 2.88, p<0.001) in the multivariate analyses. Active enthesitis showed a significant association with SpA (OR=9.20, 95% CI 4.21 to 23.20, p<0.001), and unlike the individual OMERACT ultrasound lesions it was consistently associated with most clinical measures of SpA disease activity and severity in the regression analyses. CONCLUSIONS: This large multicentre study assessed the value of different ultrasound findings of enthesitis in SpA, identifying the most discriminative ultrasound lesions and entheseal sites for SpA. Ultrasound could differentiate between SpA-related enthesitis and other forms of entheseal pathology (ie, mechanical enthesitis), thus improving the assessment of entheseal involvement in SpA.

'Double target' ultrasound monitoring of biologic therapy in psoriatic arthritis.

OBJECTIVES: We aimed to 1) evaluate by power Doppler (PD) ultrasound (US) the response to therapy of the most inflamed joint and enthesis (target sites) in psoriatic arthritis (PsA) patients starting a biologic disease-modifying anti-rheumatic drug (bDMARD); and 2) to investigate the correlation between the US response and clinical data. METHODS: Consecutive PsA patients with US synovitis and US 'active' enthesitis, starting a bDMARD, were included. The joint with the highest OMERACT-EULAR-US composite score and the enthesis with the highest PD grade (targets) were identified at baseline. The US examination and clinical assessment were performed at 0, 3 and 6 months. The response of OMERACT-EULAR-US synovitis composite score was defined as reaching a grade = 0 at follow-up examination; synovial and entheseal PD responses were defined as a PD=0 and/or a reduction of ≥2 PD grades at follow-up examination. RESULTS: Thirty patients were included. Synovitis composite score, synovial PD and entheseal PD showed significant responses at 3 and 6 months compared to baseline (p<0.01). Synovial PD responses were higher than entheseal PD responses at 3 months (71.4% vs 40.0%, p=0.01) and 6 months (77.8% vs. 46.7%, p=0.02). US synovitis responses were correlated with DAPSA (p<0.01) and MDA responses (p=0.01 for composite score, p=0.02 for PD). CONCLUSIONS: US was found sensitive for monitoring treatment response in PsA patients starting a biologic drug. Entheseal PD was less responsive than synovial PD, suggesting that enthesitis may represent a 'difficult-to-treat' domain in PsA.

Ultrasound reveals a high prevalence of CPPD in consecutive patients with knee pain.

The objective of this study is to estimate the prevalence of US findings indicative of calcium pyrophosphate deposition (CPPD) in patients with knee pain. Consecutive patients with knee pain, equally distributed among males and females in seven different age-decades (21-90 years), were enrolled in a cross-sectional study. The presence of US OMERACT-defined CPPD (medial and lateral menisci and femoral hyaline cartilage) and osteophytes (medial and lateral compartments of the tibiofemoral joint) was scored as presence/absence in both knees. Four hundred twenty participants were enrolled (210 men/210 women). Fibrocartilage and hyaline cartilage CPPDs were detected by US in 94/420 (22.4%) and 41/420 (9.8%) participants, respectively. No significant sex differences were noted. The prevalence and the extent of CPPD increased with age. Fibrocartilage and hyaline cartilage CPPDs were identified in 0/60 participants in the third decade, and in 28/60 (46.7%) and 14/60 (23.3%) participants in the ninth decade, respectively (p for trend < 0.01). While fibrocartilage and hyaline cartilage CPPD is virtually absent in subjects younger than 40 and 50 years old, their prevalence steeply increases above from these age groups. Age (aIRR, 1.03; 95% CI, 1.02-1.05), osteophyte score (aIRR, 1.40; 95% CI, 1.22-1.60), and hyaline cartilage CPPD score (aIRR, 2.68; 95% CI, 2.06-3.49) were associated with fibrocartilage CPPD score, whereas age (aIRR, 1.02; 95% CI, 1.01-1.05) and fibrocartilage CPPD score (aIRR, 2.92; 95% CI, 2.29-3.72) were associated with hyaline cartilage CPPD score in multivariable negative binomial regression analyses. In conclusion, we report the US prevalence of CPPD in patients with knee pain. Fibrocartilage CPPD occurs at a younger age and is more prevalent than hyaline cartilage CPPD. Key points • Fibrocartilage CPPD occurs at a younger age and is more prevalent than hyaline cartilage CPPD. • Fibrocartilage and hyaline cartilage CPPDs are virtually absent in subjects younger than 40 and 50 years old. • In subjects older than 80 years, fibrocartilage and hyaline cartilage CPPD prevalence rises up to 46.7% and 23.3%, respectively.

Multimodal ultrasound muscle assessment in patients with rheumatic diseases: a patient-based reliability study.

Objectives: The aim was to explore the inter-reliability of a newly developed US scanning protocol (multimodal US) for the assessment of different aspects of sarcopenia-related muscle involvement, including muscle mass, muscle quality and muscle stiffness [using point shear-wave elastography (SWE)], in patients with rheumatic and musculoskeletal diseases (RMDs). Methods: Quadriceps muscle mass (i.e. muscle thickness), muscle quality (i.e. muscle echogenicity evaluated with both a visual semi-quantitative scale and a dedicated software package for image analysis, ImageJ) and point SWE measurements were obtained by two rheumatologists (blinded to each other's evaluation) in consecutive RMD patients without previous/current myositis or neuromuscular disorders.Inter-reliability was assessed using the intraclass correlation coefficient (ICC) for continuous variables and Cohen's kappa (κ) for categorical variables. Results: A total of 45 RMD patients were enrolled [mean age 54.5 (16.0) years, male-to-female ratio 1:1.5, mean BMI 24.6 (4.6) kg/m2], 10 with PsA, 7 RA, 5 AS, 5 PMR, 4 SLE, 4 gout, 4 OA, 3 FM and 3 SSc. The grade of inter-rater reliability was excellent for muscle mass [ICC = 0.969 (0.953 < ICC < 0.979)]. Regarding muscle echogenicity, the agreement was substantial/almost perfect using the visual semi-quantitative scale (weighted linear = 0.793, weighted squared = 0.878) and excellent using ImageJ analysis [ICC = 0.916 (0.876 < ICC < 0.944)]. Finally, a good agreement was obtained for point SWE measurements [ICC = 0.76 (0.712 < ICC < 0.8)]. Conclusion: Multimodal US is a novel and reliable tool for the evaluation of different aspects of muscle involvement (muscle mass, muscle quality and muscle stiffness) in RMD patients.

Doppler Signal and Bone Erosions at the Enthesis Are Independently Associated With Ultrasound Joint Erosive Damage in Psoriatic Arthritis.

OBJECTIVE: To explore the association of the Outcome Measures in Rheumatology ultrasound (US) entheseal abnormalities with the presence of US joint bone erosions in psoriatic arthritis (PsA). METHODS: Consecutive patients with PsA were included in this cross-sectional study. Demographic and clinical variables were collected. A bilateral US assessment was carried out at the following entheses: plantar fascia, and the quadriceps, patellar (proximal and distal), and Achilles tendons. The following US entheseal abnormalities were registered: hypoechogenicity, thickening, Doppler signal < 2 mm from the bony cortex, calcification/enthesophyte, and bone erosion. The presence of US joint bone erosions was investigated at the second and fifth metacarpophalangeal joints, ulnar head, and fifth metatarsophalangeal (MTP) joint, bilaterally, as well as at the level of the most inflamed joint on physical examination. Multiple linear regression analysis was performed to identify clinical and/or US variables associated with US-detected joint bone erosions. RESULTS: A total of 104 patients with PsA were enrolled. At least 1 joint bone erosion was found in 47 of 104 patients (45.2%). Bone erosions were most frequently detected at the fifth MTP joint level (42/208 joints [20.2 %] in 32/104 patients [30.8%]). In the multivariate model, only a power Doppler (PD) signal at the enthesis (P < 0.001, standardized ß = 0.51), bone erosions at the enthesis (P = 0.02, standardized ß = 0.20), PsA disease duration (P = 0.04, standardized ß = 0.17), and greyscale joint synovitis (P = 0.03, standardized ß = 0.42) were associated with US-detected joint bone erosions. CONCLUSION: PD signal and bone erosions at the enthesis represent sonographic biomarkers of a more severe subset of PsA in terms of US-detected joint erosive damage.

In patients with acute mono/oligoarthritis, a targeted ultrasound scanning protocol shows great accuracy for the diagnosis of gout and CPPD.

OBJECTIVES: To determine an US scanning protocol with the best accuracy for the diagnosis of gout and CPPD in patients with acute mono/oligo-arthritis of unknown origin. METHODS: Patients with acute mono/oligo-arthritis in whom a joint aspiration at the most clinically involved joint (target joint) was requested were consecutively enrolled. US was performed in each patient before the arthrocentesis. The accuracy of different US findings and scanning protocols for the diagnosis of gout and CPPD was calculated. RESULTS: A total of 161 subjects were included (32 gout patients, 30 CPPD patients and 99 disease-controls). US findings had a high specificity for gout (0.92-0.96) and CPPD (0.90-0.97), while the sensitivity ranged from 0.73 to 0.85 in gout (double contour sign and tophi, respectively) and from 0.60 to 0.90 in CPPD (hyaline and fibrocartilage deposits, respectively). The US assessment of two joints bilaterally (gout: knees, MTP1 joints; CPPD: knees, wrists) plus the target joint had an excellent diagnostic sensitivity (gout: 0.91, CPPD: 0.93) and specificity (gout: 0.91, CPPD: 0.89). This targeted US scanning protocol yielded to higher diagnostic accuracy compared with the US evaluation of the target joint [gout area under the curve (AUC) 0.91 vs 0.84, P = 0.03; CPPD AUC 0.93 vs 0.84, P = 0.04] unless the target joint was the knee or the MTP1 joint in gout and the knee or the wrist in CPPD. CONCLUSIONS: A targeted US scanning protocol of two joints bilaterally plus the target joint showed an excellent accuracy (>90%) for the diagnosis of crystal arthritis in patients with acute mono/oligoarthritis.

A deep learning approach to median nerve evaluation in ultrasound images of carpal tunnel inlet.

Ultrasound (US) imaging is recognized as a useful support for Carpal Tunnel Syndrome (CTS) assessment through the evaluation of median nerve morphology. However, US is still far to be systematically adopted to evaluate this common entrapment neuropathy, due to US intrinsic challenges, such as its operator dependency and the lack of standard protocols. To support sonographers, the present study proposes a fully-automatic deep learning approach to median nerve segmentation from US images. We collected and annotated a dataset of 246 images acquired in clinical practice involving 103 rheumatic patients, regardless of anatomical variants (bifid nerve, closed vessels). We developed a Mask R-CNN with two additional transposed layers at segmentation head to accurately segment the median nerve directly on transverse US images. We calculated the cross-sectional area (CSA) of the predicted median nerve. Proposed model achieved good performances both in median nerve detection and segmentation: Precision (Prec), Recall (Rec), Mean Average Precision (mAP) and Dice Similarity Coefficient (DSC) values are 0.916 ± 0.245, 0.938 ± 0.233, 0.936 ± 0.235 and 0.868 ± 0.201, respectively. The CSA values measured on true positive predictions were comparable with the sonographer manual measurements with a mean absolute error (MAE) of 0.918 mm2. Experimental results showed the potential of proposed model, which identified and segmented the median nerve section in normal anatomy images, while still struggling when dealing with infrequent anatomical variants. Future research will expand the dataset including a wider spectrum of normal anatomy and pathology to support sonographers in daily practice.

Muscle involvement in systemic lupus erythematosus: multimodal ultrasound assessment and relationship with physical performance.

OBJECTIVES: The objectives of this study were (1) to explore US findings for muscle mass, muscle quality and muscle stiffness in SLE patients and healthy subjects; (2) to investigate the relationship between the US muscle findings and physical performance in SLE patients and healthy subjects. METHODS: Quadriceps muscle thickness was used for assessment of muscle mass, muscle echogenicity (using a visual semi-quantitative scale and grayscale analysis with histograms) for assessment of muscle quality, and point shear-wave elastography (SWE) for assessment of muscle stiffness in 30 SLE patients (without previous/current myositis or neuromuscular disorders) and 15 age-, sex- and BMI-matched healthy subjects. Hand grip strength tests and short physical performance battery (SPPB) tests were carried out in the same populations. RESULTS: No difference was observed between SLE patients and healthy subjects for quadriceps muscle thickness (35.2 mm ±s.d. 6.8 vs 34.8 mm ± s.d. 6.0, respectively, P = 0.79). Conversely, muscle echogenicity was significantly increased in SLE patients (visual semi-quantitative scale: 1.7 ± s.d. 1.0 vs 0.3 ± s.d. 0.5, respectively, P < 0.01; grayscale analysis with histograms: 87.4 mean pixels ± s.d. 18.8 vs 70.1 mean pixels ± s.d. 14.0, respectively, P < 0.01). Similarly, SWE was significantly lower in SLE patients compared with healthy subjects {1.5 m/s [interquartile range (IQR) 0.3] vs 1.6 m/s (IQR 0.2), respectively, P = 0.01}. Muscle echogenicity was inversely correlated with grip strength (visual semi-quantitative scale, Rho: -0.47, P = 0.01; grayscale analysis with histograms, Rho: -0.41, p < 0.01) and SPPB (visual semi-quantitative scale, Rho: -0.50, P < 0.01; grayscale analysis with histograms Rho: -0,46, P < 0.01). CONCLUSIONS: US assessment of muscle echogenicity and stiffness is useful for the early detection of muscle involvement in SLE patients.

Reliability assessment of the definition of ultrasound enthesitis in SpA: results of a large, multicentre, international, web-based study.

OBJECTIVES: To investigate the reliability of the OMERACT US Task Force definition of US enthesitis in SpA. METHODS: In this web exercise, based on the evaluation of 101 images and 39 clips of the main entheses of the lower limbs, the elementary components included in the OMERACT definition of US enthesitis in SpA (hypoechoic areas, entheseal thickening, power Doppler signal at the enthesis, enthesophytes/calcifications, bone erosions) were assessed by 47 rheumatologists from 37 rheumatology centres in 15 countries. Inter- and intra-observer reliability of the US components of enthesitis was calculated using Light's kappa, Cohen's kappa, Prevalence And Bias Adjusted Kappa (PABAK) and their 95% CIs. RESULTS: Bone erosions and power Doppler signal at the enthesis showed the highest overall inter-reliability [Light's kappa: 0.77 (0.76-0.78), 0.72 (0.71-0.73), respectively; PABAK: 0.86 (0.86-0.87), 0.73 (0.73-0.74), respectively], followed by enthesophytes/calcifications [Light's kappa: 0.65 (0.64-0.65), PABAK: 0.67 (0.67-0.68)]. This was moderate for entheseal thickening [Light's kappa: 0.41 (0.41-0.42), PABAK: 0.41 (0.40-0.42)], and fair for hypoechoic areas [Light's kappa: 0.37 (0.36-0.38); PABAK: 0.37 (0.37-0.38)]. A similar trend was observed in the intra-reliability exercise, although this was characterized by an overall higher degree of reliability for all US elementary components compared with the inter-observer evaluation. CONCLUSIONS: The results of this multicentre, international, web-based study show a good reliability of the OMERACT US definition of bone erosions, power Doppler signal at the enthesis and enthesophytes/calcifications. The low reliability of entheseal thickening and hypoechoic areas raises questions about the opportunity to revise the definition of these two major components for the US diagnosis of enthesitis.

Development of a convolutional neural network for the identification and the measurement of the median nerve on ultrasound images acquired at carpal tunnel level.

BACKGROUND: Deep learning applied to ultrasound (US) can provide a feedback to the sonographer about the correct identification of scanned tissues and allows for faster and standardized measurements. The most frequently adopted parameter for US diagnosis of carpal tunnel syndrome is the increasing of the cross-sectional area (CSA) of the median nerve. Our aim was to develop a deep learning algorithm, relying on convolutional neural networks (CNNs), for the localization and segmentation of the median nerve and the automatic measurement of its CSA on US images acquired at the proximal inlet of the carpal tunnel. METHODS: Consecutive patients with rheumatic and musculoskeletal disorders were recruited. Transverse US images were acquired at the carpal tunnel inlet, and the CSA was manually measured. Anatomical variants were registered. The dataset consisted of 246 images (157 for training, 40 for validation, and 49 for testing) from 103 patients each associated with manual annotations of the nerve boundary. A Mask R-CNN, state-of-the-art CNN for image semantic segmentation, was trained on this dataset to accurately localize and segment the median nerve section. To evaluate the performances on the testing set, precision (Prec), recall (Rec), mean average precision (mAP), and Dice similarity coefficient (DSC) were computed. A sub-analysis excluding anatomical variants was performed. The CSA was automatically measured by the algorithm. RESULTS: The algorithm correctly identified the median nerve in 41/49 images (83.7%) and in 41/43 images (95.3%) excluding anatomical variants. The following metrics were obtained (with and without anatomical variants, respectively): Prec 0.86 ± 0.33 and 0.96 ± 0.18, Rec 0.88 ± 0.33 and 0.98 ± 0.15, mAP 0.88 ± 0.33 and 0.98 ± 0.15, and DSC 0.86 ± 0.19 and 0.88 ± 0.19. The agreement between the algorithm and the sonographer CSA measurements was excellent [ICC 0.97 (0.94-0.98)]. CONCLUSIONS: The developed algorithm has shown excellent performances, especially if excluding anatomical variants. Future research should aim at expanding the US image dataset including a wider spectrum of normal anatomy and pathology. This deep learning approach has shown very high potentiality for a fully automatic support for US assessment of carpal tunnel syndrome.

Ultrasound findings of calcium pyrophosphate deposition disease at metacarpophalangeal joints.

OBJECTIVE: To explore the spectrum of articular and peri-articular ultrasound (US) findings at metacarpophalangeal (MCP) joints in calcium pyrophosphate (CPP) deposition disease (CPPD). METHODS: Consecutive CPPD patients (chronic CPP crystal inflammatory arthritis or OA with CPPD), and age- and sex-matched controls with RA were prospectively enrolled. Patients underwent bilateral US examination of MCP joints. CPP deposits, synovial inflammation, osteophytes, cartilage damage and bone erosions were recorded. RESULTS: Sixty CPPD patients (33, 55.0% with OA with CPPD and 27, 45.0% with chronic CPP crystal inflammatory arthritis) and 40 RA patients were enrolled. CPP deposits were detected in 24 (40.0%) CPPD patients and in 3 (7.5%) RA patients (P <0.01). In CPPD patients, different types of CPP deposits were identified at MCP joints: 17 (28.3%) patients had dorsal capsuloligamentous deposits, 14 (23.3%) intra-cartilaginous deposits, 13 (21.7%) lateral capsuloligamentous deposits, 12 (20.0%) intra-articular deposits, eight (13.3%) double contour sign and five (8.3%) flexor digitorum tendons' deposits. CPPD patients with chronic CPP crystal inflammatory arthritis showed more US findings indicating synovial inflammation and CPP deposits than those with OA with CPPD. Conversely, a higher prevalence of US features indicating structural damage was noted in this latter phenotype. CPP deposits and bone erosions were the US findings with the highest value for diagnosing chronic CPP crystal inflammatory arthritis and RA, respectively. CONCLUSION: This study provides pictorial evidence of the broad spectrum of US findings indicating CPP deposits at MCP joints in CPPD. Furthermore, we reported different US patterns in different CPPD phenotypes.

Reliability assessment of ultrasound muscle echogenicity in patients with rheumatic diseases: Results of a multicenter international web-based study.

Objectives: To investigate the inter/intra-reliability of ultrasound (US) muscle echogenicity in patients with rheumatic diseases. Methods: Forty-two rheumatologists and 2 radiologists from 13 countries were asked to assess US muscle echogenicity of quadriceps muscle in 80 static images and 20 clips from 64 patients with different rheumatic diseases and 8 healthy subjects. Two visual scales were evaluated, a visual semi-quantitative scale (0-3) and a continuous quantitative measurement ("VAS echogenicity," 0-100). The same assessment was repeated to calculate intra-observer reliability. US muscle echogenicity was also calculated by an independent research assistant using a software for the analysis of scientific images (ImageJ). Inter and intra reliabilities were assessed by means of prevalence-adjusted bias-adjusted Kappa (PABAK), intraclass correlation coefficient (ICC) and correlations through Kendall's Tau and Pearson's Rho coefficients. Results: The semi-quantitative scale showed a moderate inter-reliability [PABAK = 0.58 (0.57-0.59)] and a substantial intra-reliability [PABAK = 0.71 (0.68-0.73)]. The lowest inter and intra-reliability results were obtained for the intermediate grades (i.e., grade 1 and 2) of the semi-quantitative scale. "VAS echogenicity" showed a high reliability both in the inter-observer [ICC = 0.80 (0.75-0.85)] and intra-observer [ICC = 0.88 (0.88-0.89)] evaluations. A substantial association was found between the participants assessment of the semi-quantitative scale and "VAS echogenicity" [ICC = 0.52 (0.50-0.54)]. The correlation between these two visual scales and ImageJ analysis was high (tau = 0.76 and rho = 0.89, respectively). Conclusion: The results of this large, multicenter study highlighted the overall good inter and intra-reliability of the US assessment of muscle echogenicity in patients with different rheumatic diseases.

Learning-Based Median Nerve Segmentation From Ultrasound Images For Carpal Tunnel Syndrome Evaluation.

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy. Ultrasound imaging (US) may help to diagnose and assess CTS, through the evaluation of median nerve morphology. To support sonographers, this paper proposes a fully-automatic deep-learning approach to median nerve segmentation from US images. The approach relies on Mask R-CNN, a convolutional neural network that is trained end-to-end. The segmentation head of Mask R-CNN is here evaluated with three different configurations, with the goal of studying the effect of the segmentation-head output resolution on the overall Mask R-CNN segmentation performance. For this study, we collected and annotated a dataset of 151 images acquired in the actual clinical practice from 53 subjects with CTS. To our knowledge, this is the largest dataset in the field in terms of subjects. We achieved a median Dice similarity coefficient equal to 0.931 (IQR = 0.027), demonstrating the potentiality of the proposed approach. These results are a promising step towards providing an effective tool for CTS assessment in the actual clinical practice.

Enthesitis in Psoriatic Arthritis, the Sonographic Perspective.

PURPOSE OF REVIEW: To provide an overview of the ultrasound (US) studies focusing on enthesitis in psoriatic arthritis (PsA). RECENT FINDINGS: Last-generation US equipment has demonstrated the ability to detect subtle morphostructural and vascular abnormalities at entheseal level. US is able to identify pathologic changes in both "classical" (i.e., the site of attachment of tendons, ligaments, and joint capsules into the bone) and "functional" entheses (i.e., anatomical regions where tendons or ligaments wrap around bony pulleys). US has the potential to be the first-line method in the assessment of enthesitis. In the present review we critically discussed the current definitions of US enthesitis, the scoring systems, and the main fields of application (i.e., the detection of enthesitis in PsA and psoriasis, the identification of different disease subsets, and the assessment of response to treatment).

Imaging of Joint and Soft Tissue Involvement in Systemic Lupus Erythematosus.

PURPOSE OF REVIEW: To highlight the potential uses and applications of imaging in the assessment of the most common and relevant musculoskeletal (MSK) manifestations in systemic lupus erythematosus (SLE). RECENT FINDINGS: Ultrasound (US) and magnetic resonance imaging (MRI) are accurate and sensitive in the assessment of inflammation and structural damage at the joint and soft tissue structures in patients with SLE. The US is particularly helpful for the detection of joint and/or tendon inflammation in patients with arthralgia but without clinical synovitis, and for the early identification of bone erosions. MRI plays a key role in the early diagnosis of osteonecrosis and in the assessment of muscle involvement (i.e., myositis and myopathy). Conventional radiography (CR) remains the traditional gold standard for the evaluation of structural damage in patients with joint involvement, and for the study of bone pathology. The diagnostic value of CR is affected by the poor sensitivity in demonstrating early structural changes at joint and soft tissue level. Computed tomography allows a detailed evaluation of bone damage. However, the inability to distinguish different soft tissues and the need for ionizing radiation limit its use to selected clinical circumstances. Nuclear imaging techniques are valuable resources in patients with suspected bone infection (i.e., osteomyelitis), especially when MRI is contraindicated. Finally, dual energy X-ray absorptiometry represents the imaging mainstay for the assessment and monitoring of bone status in patients with or at-risk of osteoporosis. Imaging provides relevant and valuable information in the assessment of MSK involvement in SLE.

Ultrasound definition of enthesitis in spondyloarthritis and psoriatic arthritis: arrival or starting point?

Enthesitis has a key role in the diagnosis, classification and management of patients with spondyloarthritis and psoriatic arthritis. Clinical assessment of enthesitis is known to be inaccurate mainly due to its poor specificity. In this context, ultrasound has the potential to improve the evaluation of enthesitis and, therefore, the management of patients with spondyloarthritis and psoriatic arthritis. In this viewpoint, we review the Outcome Measures in Rheumatology (OMERACT) definitions for ultrasound enthesitis, highlighting their current limits and potential implications on rheumatology research and clinical practice.

The sonographic identification of cortical bone interruptions in rheumatoid arthritis: a morphological approach.

Bone erosions are the hallmark of structural damage in rheumatoid arthritis (RA). Among imaging techniques, ultrasonography (US) has emerged as an accurate, reliable, repeatable, low-cost and non-invasive imaging modality to detect erosive changes in RA. However, small interruptions of the cortical bone detectable by last generation US equipment do not necessarily represent bone erosions. According to the available data, in addition to cortical bone interruption itself, only a few morphological US findings have been proposed to define RA bone erosions. However, other additional features may be considered to facilitate the interpretation of US cortical bone interruptions in RA. These could be summarised using the following four domains: size, site, shape and scenery. This hypothesis article provides a critical literature review of US features characteristic of RA bone erosions and pictorial evidence supporting the potential role of a morphological analysis in the US identification of bone erosions in RA patients. PLAIN LANGUAGE SUMMARY: The ultrasonographic morphology of cortical interruptions is helpful for the identification of bone erosions in rheumatoid arthritis: the "four Ss" approach Bone erosions are characteristic features of rheumatoid arthritis. They are associated with a more aggressive disease and with irreversible physical disability. In recent years, ultrasonography has emerged as an accurate and reliable technique for the detection of bone erosions, that appear as interruptions of the cortical bone with variable size. However, cortical bone interruptions do not necessarily represent bone erosions. Since bone erosions represent the earliest evidence of the destructive behaviour of RA, their identification is crucial.Besides the cortical interruption itself, only a few morphological ultrasonographic features were proposed to characterise bone erosions in rheumatoid arthritis.We believe that a morphological approach, including size, site, shape and scenery, may be considered to facilitate the interpretation of ultrasonographic cortical bone interruptions in rheumatoid arthritis.In this hypothesis article we carried out a critical review of the scientific literature and provided extensive pictorial evidence of the ultrasonographic spectrum of cortical interruptions supporting the potential role of considering the "four Ss" for the ultrasonographic identification of bone erosions in rheumatoid arthritis.