Current state of musculoskeletal ultrasound in paediatric rheumatology: results of an international survey

Prevalence of ultrasound and clinical findings suggestive of inflammatory arthritis in children with skin psoriasis

OBJECTIVE

To evaluate the prevalence of clinical and US (grey-scale and Doppler) abnormalities in joints, periarticular structures and nails of children affected by skin psoriasis (PsO).

METHODS

We conducted a cross-sectional study including consecutive children affected by PsO. A systematic clinical and US evaluation of joints, entheses, tendons and nails were performed by independent examiners blinded to each other's assessment.

RESULTS

A total of 57 children [26 girls (46%)] with a mean age of 9 years (s.d. 4) were divided into two groups, asymptomatic (Asy, 42 children) and symptomatic (Sy, 15 children), according to musculoskeletal pain. Differences were observed between the two groups in relation to age [9 years (s.d. 3) vs 11 years (s.d. 4), P < 0.05], PsO duration [2.4 years (s.d. 2.4) vs 5.4 years (s.d. 3.9), P < 0.001], systemic treatment [23 (54.8%) vs 2 [13.3%], P < 0.01], tender joint count [0 vs 12 children (80%), P < 0.001], swollen joint count [0 vs 3 children (20%), P < 0.01] and entheseal pain [0 vs 10 (66.7%), P < 0.001] in Asy and Sy children, respectively. US evaluation showed statistically significant differences between the Asy and Sy groups for the presence of US abnormalities [16/42 (38%) vs 12/15 (80%)], synovitis [1/42 (2%) vs 4/15 (25%)] and enthesitis [4/42 (9.5%) vs 5/15 (33%)]. Three children in the Sy group were classified with juvenile PsA (JPsA).

CONCLUSIONS

US abnormalities were higher in the Sy group, with synovitis and enthesitis as the most prevalent findings. Asy patients were more frequently under systemic treatment. US and a systematic clinical evaluation are useful tools for detecting subclinical JPsA in children with PsO and musculoskeletal symptoms.

Needs Assessment of Musculoskeletal Ultrasound Training in North American Pediatric Rheumatology Fellowship Programs

OBJECTIVE

Musculoskeletal ultrasound (MSUS) is widely used in adult rheumatology practice for diagnosis of arthritis and procedural guidance; however, it is not yet common practice in pediatric rheumatology. MSUS is advantageous to the pediatric population because it lacks radiation and eliminates need for sedation. This study aims to assess interest in, access to, and barriers to MSUS training in pediatric rheumatology fellowship programs in North America.

METHODS

A survey was developed by pediatric rheumatology providers with experience in medical and/or MSUS education and distributed via REDCap anonymously in March 2022 (Supplementary Material). Eligible participants included current and recently graduated (<1 year) pediatric rheumatology fellows at a North American program. Descriptive statistics and bivariate analyses using design-based Pearson chi-squared tests were performed.

RESULTS

Overall response rate was 78% (88/113), and 75% reported some form of MSUS training during fellowship. Only 36% indicated their program had a formal MSUS curriculum. Of those with MSUS training, 23% reported adult-only MSUS education. Eighty-four percent felt MSUS would be beneficial to their career. Major barriers to MSUS training included lack of MSUS-trained faculty, lack of time, and lack of hands-on MSUS sessions. Those who had access to MSUS training were significantly more interested in MSUS than those without (P = 0.0036).

CONCLUSION

This study demonstrates that North American pediatric rheumatology fellows have a strong interest in learning MSUS, but they face significant challenges in accessing MSUS training (lack of MSUS-trained faculty, time, and access to hands-on training). MSUS should be incorporated into fellowship curriculum; however, implementation remains a challenge.

Validity of ultrasonography in detecting enthesitis in children: A systematic literature review

OBJECTIVE

A systematic review to assess the value of ultrasonography (US) for detecting enthesitis in juvenile idiopathic arthritis (JIA).

METHODS

PubMed and Embase databases were searched for articles published from January 1966 to May 2021; we selected those meeting the inclusion criteria according to the US definition of enthesitis and metric properties studied. We assessed the clinical features of the population, study design, the type and number of entheses examined, the definition and scoring system of US enthesitis and metric properties according to the OMERACT filter (truth, discrimination and feasibility). The quality of the studies was evaluated with the Quality Assessment of Diagnostic Accuracy Studies 2.

RESULTS

Five publications met the inclusion criteria (26 to 146 patients and 1 to 10 bilaterally examined entheses). All studies focused on lower-limb entheses. The elementary lesions included in the definition of adult enthesitis were generally assessed. Few studies reported US reliability and none evaluated sensitivity to change of US. US revealed entheseal abnormalities in 9.4 to 53% of JIA patients and 20 to 83% of enthesitis-related arthritis cases. No significant abnormalities were found in healthy children. US findings were poorly correlated with clinical examination. The overall quality of the studies was low, mainly because of the lack of a reference standard.

CONCLUSION

US is a sensitive tool to detect entheseal abnormalities in JIA. The current evidence highlights that a standardized US definition of enthesitis in children is lacking and US criteria and discriminant validity have not been established.

Ultrasonography in Pediatric Rheumatology

This review highlights the increasing evidence from the last few years supporting the use of musculoskeletal ultrasonography (MSUS) in the evaluation and management of patients with pediatric rheumatic diseases, particularly focusing on juvenile idiopathic arthritis. Recently developed definitions for the sonographic appearance of healthy and pathologic joints in children are discussed. Further topics explored include how MSUS enhances the diagnosis of inflammatory joint disease (synovitis, enthesitis, tenosynovitis), including the detection of subclinical synovitis. There is a brief summary on the use of ultrasonography in the evaluations of myositis, Sjögren syndrome, and scleroderma.

Comparison Between Clinical and Ultrasound Assessment of the Ankle Region in Children With Juvenile Idiopathic Arthritis

OBJECTIVE

To compare the frequency of joint and tendon disease on ultrasound (US) and clinical examination, and to investigate agreement between US and clinical evaluation in ankles with clinically active juvenile idiopathic arthritis (JIA).

METHODS

US and clinical evaluation were performed independently in the joint and tendon compartments of 105 ankles. Gray-scale (GS) US and power Doppler (PD) US joint abnormalities were scored on a 4-point semiquantitative scale. A joint with a GS score ≥2 and/or a PD score ≥1 was defined as active on US. Agreement was tested using kappa statistics.

RESULTS

A total of 163 joints in 89 ankles had active synovitis on US. The tibiotalar (TT) joint was the most commonly affected joint on US and on clinical evaluation. The intertarsal (IT) joint and the subtalar (ST) joint were the second in frequency on US and on clinical evaluation, respectively. Tenosynovitis was found more commonly on US than on clinical evaluation (70.5% and 32.4%, respectively), and was more frequent in the medial and lateral than in the anterior tendon compartment. Isolated tenosynovitis was detected on US in 12 of 105 ankles. Agreement between US and clinical evaluation for detection of active synovitis and tenosynovitis was less than acceptable (κ <0.4). No correlation was found between any feature of active disease recorded on clinical evaluation (joint swelling, tenderness/pain on motion, and restricted motion) and active synovitis on US in the TT joint, ST joint, and IT joint.

CONCLUSION

Coupling clinical evaluation with US aids in correctly localizing pathology. US training of practitioners is recommended to manage ankle disease in JIA.

Rheumatoid Hand and Other Hand-deforming Rheumatic Conditions

The hand and wrist are commonly involved in rheumatic conditions, particularly rheumatoid arthritis and other systemic connective tissue diseases. With spondyloarthritis, hand and wrist involvement frequently occurs in psoriatic arthritis but generally does not occur in the remaining subtypes. The hand and wrist may also be affected in various metabolic and endocrine diseases, but these lie beyond the scope of this review.Radiographs may demonstrate the presence of joint space narrowing, bone loss, cysts and erosions, malalignments, and osteolysis. They may also show regions of soft tissue swelling or thinning, and detect calcifications. Ultrasonography and magnetic resonance imaging (MRI) enable evaluation of the soft tissues, particularly the synovium, tenosynovium, and tendons. Furthermore, erosions are better demonstrated than on radiographs. MRI allows evaluation of periarticular bone marrow edema.This article discusses typical imaging features of the hand and wrist in rheumatologic conditions including the advantages and limitations of the various methods.

Musculoskeletal ultrasound assessment in pediatric knee hypermobility: a case control study

BACKGROUND

While musculoskeletal ultrasound (MSUS) use in pediatric rheumatology is becoming more common, the majority of pediatric MSUS literature continues to focus on ultrasound findings in healthy children and juvenile idiopathic arthritis with little discussion of other musculoskeletal problems that may mimic arthritis such as joint hypermobility. Chronic joint pain related to hypermobility is a common referral to pediatric rheumatology clinics. Our aim is to describe the musculoskeletal ultrasound (MSUS) characteristics of the knee in a population with joint hypermobility and pain in comparison to control participants.

METHODS

Participants were recruited into three groups for a case-control study. Case group participants had knee hypermobility and pain symptoms (H + P). Participants in one control group had knee hypermobility without pain symptoms (H-P), and participants in the other control group had no knee hypermobility or pain symptoms (NP). B-mode and Doppler MSUS images were obtained and scored for each knee. Descriptive statistics are used for demographic variables and MSUS findings. Regression analysis is used to evaluate risk of synovial effusion and higher synovial effusion/hypertrophy quantitative score.

RESULTS

MSUS assessment was performed on 91 knees of 50 participants. H + P knees were more likely to have positive findings noted on MSUS (94% vs. 70% of H-P and 74% of NP knees, p = 0.043). Patellar tendon hyperemia was more common in H + P knees (52%, vs. 19% among H-P and 23% among NP, p = 0.025). Participants who reported taking scheduled non-steroidal anti-inflammatory drugs (NSAIDs) had an increased risk of synovial effusion (RR = 1.83, 95% CI = 1.07-2.30, p = 0.026) and a trend towards increased risk of a higher synovial effusion/hypertrophy quantitative score (RR = 1.77, 95% CI = 0.92-3.38, p = 0.086).

CONCLUSIONS

While positive MSUS findings were frequent in all participants, patellar tendon hyperemia was more frequent in participants with knee hypermobility and pain symptoms. Additionally, reported use of NSAIDs was associated with an increased risk of synovial effusion and higher synovial effusion/hypertrophy quantitative score. Further study should assess correlation between tendon abnormalities and degree of pain symptoms as well as the effect of NSAIDs on MSUS findings.

Imaging in juvenile idiopathic arthritis - international initiatives and ongoing work

Imaging is increasingly being integrated into clinical practice to improve diagnosis, disease control and outcome in children with juvenile idiopathic arthritis. Over the last decades several international groups have been launched to standardize and validate different imaging techniques. To enhance transparency and facilitate collaboration, we present an overview of ongoing initiatives.

Imaging of the knee in juvenile idiopathic arthritis

In juvenile idiopathic arthritis (JIA), imaging is increasingly used in clinical practice. In this paper we discuss imaging of the knee, the clinically most commonly affected joint in JIA. In the last decade, a number of important steps have been made in the development of imaging outcome measures in children with JIA knee involvement. Ultrasound is undergoing a fast validation process, which should be accomplished within the next few years. The validation processes of MRI as an imaging biomarker for clinical trials in the JIA knee are at an advanced stage, with important data available on the feasibility, reliability and validity of the Juvenile Arthritis MRI Scoring system. Moreover, both US and MRI data are emerging on the normal appearance of the growing knee joint.

Patients with juvenile idiopathic arthritis in clinical remission with positive power Doppler signal in joint ultrasonography have an increased rate of clinical flare: a prospective study

BACKGROUND

Ultrasonography (US) studies carried out on joints of juvenile idiopathic arthritis (JIA) patients in clinical remission demonstrate the presence of subclinical synovitis. The significance of subclinical synovitis and the positive power Doppler (PD) signal on US in JIA in clinical remission is not well understood. The objectives of this study were to assess whether the changes detected by US in patients with JIA in clinical remission can predict disease flare and to evaluate factors associated with flare and joint damage over 30 months of follow-up.

METHODS

A prospective study was performed with clinical and ultrasound evaluation in 34 joints of JIA patients in clinical remission. Clinical evaluation including physical exam, functional capacity and inflammatory markers was performed at baseline and every six months thereafter, for a total period of 30 months. US evaluation included presence of synovitis, PD signal and erosion at baseline and every 12 months thereafter. Subclinical synovitis was defined when there was synovitis with or without positive PD signal in US joints of patients in clinical remission. Flare was defined as any joint presenting clinical arthritis requiring therapy modification.

RESULTS

We evaluated a total of 35 patients, 28 (80%) girls, 14 (40%) persistent oligoarticular subtype, 12 (34.3%) oligoarticular extended and 9 (25.7%) polyarticular and 26 (74.3%) in remission on medication. Twenty (57.1%) patients flared. The risk of flare was five times higher in patients with positive PD signal and 14 times higher in patients in remission on medication. Regarding the assessment of joints after 6 months and 12 months of US evaluation, 70/3162 (2.2%) joints and 80/2108 (3.8%) joints flared, respectively. Joints with subclinical synovitis with positive PD signal flared more after 6 and 12 months. Twenty five of 2108 (1.2%) joints showed erosion over time. Joints with subclinical synovitis with or without positive PD signal showed more erosion.

CONCLUSIONS

Patients in remission on medication with subclinical synovitis with positive PD signal on US have a higher risk of flare, therefore they should be monitored closely during treatment. In the same way, joints with subclinical synovitis with or without positive PD signal should be monitored due to the risk of flare and joint damage.

Age-dependent arthrosonographic reference values of the hip joint in healthy children and adolescents - a cross-sectional multicenter ultrasound study

BACKGROUND

Musculoskeletal US is a noninvasive imaging method for diagnosing and monitoring inflammatory rheumatic diseases.

OBJECTIVES

To develop age- and gender-related arthrosonographic reference intervals for the hip joint of healthy children and adolescents.

MATERIALS AND METHODS

In a cross-sectional US study, we examined both hip joints of 445 children and adolescents with an age range of 1 year to 18 years. We measured the distance between the bone surface and the outer margin of the joint capsule to define the bone-capsule distance, the joint capsule and cartilage thickness, and the capsule layer thickness. Reference values were calculated. The shape of the joint capsule and bone-capsule junction zone were analyzed qualitatively. An intraobserver analysis was performed.

RESULTS

Bone-capsule distance, capsule thickness and the anterior capsule layer increase with age. In contrast, joint cartilage decreases. The posterior capsule layer exhibited constant thickness across all age groups. The difference between both body sides and gender was collectively less than 0.5 mm. The intraobserver variations were within the calculated reference intervals. The insertion of the capsule to the bone was mostly a peaked one. The capsule shape had a convex or straight configuration in a neutral position and a concave position during outward rotation. The intraobserver analysis revealed good to very good concordance.

CONCLUSION

We propose age- and gender-related reference intervals for the bone-capsule distance, joint capsule and cartilage thickness of the hip.

Preliminary Definitions for the Sonographic Features of Synovitis in Children

OBJECTIVE

Musculoskeletal ultrasonography (US) has the potential to be an important tool in the assessment of disease activity in childhood arthritides. To assess pathology, clear definitions for synovitis need to be developed first. The aim of this study was to develop and validate these definitions through an international consensus process.

METHODS

The decision on which US techniques to use and the components to be included in the definitions, as well as the final wording, were developed by 31 US experts in a consensus process. A Likert scale of 1-5 (where 1 = complete disagreement and 5 = complete agreement) was used. A minimum of 80% of the experts scoring 4 or 5 was required for final approval. The definitions were then validated on 120 standardized US images of the wrist, metacarpophalangeal joints, and tibiotalar joints, displaying various degrees of synovitis at various ages.

RESULTS

B-mode and Doppler should be used for assessing synovitis in children. A US definition of the various components (i.e., synovial hypertrophy, effusion, and Doppler signal within the synovium) was developed. The definition was validated on still images with a median of 89% of participants (range 80-100) scoring it as 4 or 5 on a Likert scale.

CONCLUSION

US definitions of synovitis and its elementary components covering the entire pediatric age range were successfully developed through a Delphi process and validated in a web-based still-images exercise. These results provide the basis for the standardized US assessment of synovitis in clinical practice and research.

Prominent midfoot involvement in children with enthesitis-related arthritis category of juvenile idiopathic arthritis

Foot involvement is common in juvenile idiopathic arthritis (JIA) but is often unrecognized and difficult to treat. This study was done to assess clinical and radiological involvement of the feet and its impact on function in Indian children with enthesitis-related arthritis (ERA). We enrolled consecutive children with ERA with disease duration of less than 5 years. All patients underwent clinical examination of the feet and filled the juvenile arthritis foot index (JAFI) questionnaire. Ultrasound (US) of foot joints and entheses and extremity magnetic resonance imaging (MRI) scan of one foot were done. Fifty-five patients (53 boys), with median 14 years and disease duration 1.9 years, were included. Thirty-seven of 46 were HLA-B27-positive. Mean juvenile spondyloarthritis disease activity (JSpADA) index and juvenile idiopathic arthritis disease activity scrore-10 (JADAS10) scores were 4 and 14.25. Forty-six had history of foot pain, 36 had foot involvement on examination (15 ankle, 8 subtalar, 24 midfoot, 10 forefoot, and 21 tendoachilles), and 7 had plantar fascia involvement. On US (N = 55), 16 had ankle involvement and 8 had subtalar involvement, and 19 patients had midfoot arthritis, 24 had tendoachilles enthesitis, and 11 had plantar fasciitis. On MRI (N = 50), 27 had midfoot involvement. Thirty-three had bone edema. Fourteen had midfoot enthesitis and 17 had tenosynovitis. Clinical and US had 82% concordance at the midfoot and 90% at the ankle. MRI had 74% concordance with examination and 72% with US at the midfoot. The median JAFI scores were as follows: total JAFI = 4 (0-11), impairment = 1, activity limitation = 2, and participation restriction = 1. JAFI total and individual domains correlated with JADAS10, JSpADAS, and childhood health assessment questionnaire (CHAQ) but not duration of foot disease. JAFI was higher in children with midfoot arthritis on US. Foot joints and entheses are involved in a substantial proportion of patients with ERA patients and the midfoot is commonly involved. Foot disease produces significant functional limitation.

The OMERACT Ultrasound Group: A Report from the OMERACT 2016 Meeting and Perspectives

Objective.

To provide an update from the Outcome Measures in Rheumatology (OMERACT) Ultrasound Working Group on the progress for defining ultrasound (US) minimal disease activity threshold at joint level in rheumatoid arthritis (RA) and for standardization of US application in juvenile idiopathic arthritis (JIA).

Methods.

For minimal disease activity, healthy controls (HC) and patients with early arthritis (EA) who were naive to disease-modifying antirheumatic drugs were recruited from 2 centers. US was performed of the hands and feet, and scored semiquantitatively (0–3) for synovial hypertrophy (SH) and power Doppler (PD). Synovial effusion (SE) was scored a binary variable. For JIA, a Delphi approach and subsequent validation in static images and patient-based exercises were used to developed preliminary definitions for synovitis and a scoring system.

Results.

For minimal disease activity, 7% HC had at least 1 joint abnormality versus 30% in the EA group. In HC, the findings of SH and PD were predominantly grade 1 whereas all grades were seen in the EA cohort, but SE was rare. In JIA, synovitis can be diagnosed based on B-mode findings alone because of the presence of physiological vascularization. A semiquantitative scoring system (0–3) for synovitis for both B-mode and Doppler were developed in which the cutoff between Doppler grade 2 and grade 3 was 30%.

Conclusion.

The first step has been taken to define the threshold for minimal disease activity in RA by US and to define and develop a scoring system for synovitis in JIA. Further steps are planned for the continuous validation of US in these areas.

[Imaging options in pediatric rheumatology]

There has been growing interest in the use of imaging modalities in pediatric rheumatology for the past 15 years. Nowadays, highly sensitive imaging techniques can be used to detect early stages of pediatric rheumatic diseases in addition to the physical examination. Magnetic resonance imaging and musculoskeletal ultrasound play the most important role. Moreover, these two techniques are of great value in differential diagnostics and therapy monitoring. The use of imaging methods with a high radiation exposure could therefore be greatly reduced over the last decade.

Imaging in paediatric rheumatology: Is it time for imaging?

Juvenile idiopathic arthritis (JIA) is a heterogeneous group of arthritides characterized by chronic synovial inflammation that can lead to structural damage. The main objective of JIA therapies is to induce disease control to avoid disability in childhood. The advances in therapeutic effectiveness have created a need to search for imaging tools that describe more precisely disease activity in children with JIA. Musculoskeletal ultrasound and magnetic resonance imaging have demonstrated to be more sensitive than clinical examination in early detection of synovitis. These modalities can detect both inflammatory and destructive changes. The unique characteristics of the growing skeleton and a scarce validation of imaging in children result in important challenges in evaluating paediatric population. This review describes indications and limitations of these imaging techniques and suggests some advices for a rational use in the management of JIA in clinical practice.

Pediatric musculoskeletal ultrasound: age- and sex-related normal B-mode findings of the knee

Musculoskeletal ultrasound (MSUS) is an important tool for evaluating disease activity, therapeutic progress, and remission status of rheumatic diseases in children. Knowledge of age-related normal findings is essential when interpreting pathological findings such as those seen in juvenile idiopathic arthritis. To evaluate normal findings of the knee joint, we recorded age-related stages of musculoskeletal development in the knee of 435 healthy children between 1 and 18 years of age using high-resolution B-mode MSUS. We determined approximate age- and sex-related norms for the suprapatellar recess size, ossified patella size, and distal femoral intercondylar cartilage thickness. In almost all age-groups, over 64 % of children had visible fluid accumulation in the suprapatellar recess. Significant correlations were found between chronological age and the suprapatellar recess size and ossified patella length (p < 0.05). An age-dependent decrease in intercondylar cartilage thickness of the distal femoral epiphysis was found in children between 10 and 18 years of age. High-resolution B-mode MSUS is an excellent tool for assessing joint and skeletal development in children. Our reference data can be used to discriminate better between normal physiological findings and pathological abnormalities.

Ultrasound in juvenile idiopathic arthritis

BACKGROUND

In the recent years, musculoskeletal ultrasound (MSUS) has been regarded as especially promising in the assessment of juvenile idiopathic arthritis (JIA), as a reliable method to precisely document and monitor the synovial inflammation process.

MAIN CONTENT

MSUS is particularly suited for examination of joints in children due to several advantages over other imaging modalities. Some challenges should be considered for correct interpretation of MSUS findings in children, due to the peculiar features of the growing skeleton. MSUS in JIA is considered particularly useful for its ability to detect subclinical synovitis, to improve the classification of patients in JIA subtypes, for the definition of remission, as guidance to intraarticular corticosteroid injections and for capturing early articular damage. Current evidence and applications of MSUS in JIA are documented by several authors. Recent advances and insights into further investigations on MSUS in healthy children and in JIA patients are presented and discussed in the present review.

CONCLUSIONS

MSUS shows great promise in the assessment and management of children with JIA. Nonetheless, anatomical knowledge of sonographic changes over time, underlying immunopathophysiology, standardization and validation of MSUS in healthy children and in patients with JIA are still under investigation. Further research and educational efforts are required for expanding this imaging modality to more clinicians in their daily practice.

Ultrasonography in pediatric rheumatology in Latin America. Expanding the frontiers

For the past two decades, musculoskeletal ultrasonography (MSKUS) has developed exponentially and has become an essential tool in rheumatology practice. This development has been far more limited in pediatric rheumatology which is partially related to deficits in the evidence base. Many studies have shown that MSKUS is more sensitive than the clinical examination for detecting synovitis and enthesitis in adults. At the same time, there is a lack of studies demonstrating its validity, reliability, and reproducibility in pediatric rheumatology. In addition, clear definitions for the normal pediatric joint and enthesis as well as various findings in pathology associated with juvenile idiopathic arthritis (JIA) and juvenile spondyloarthritis (JSpA) have only started to emerge. Most of this work is being done through the Outcome Measurement in Rheumatology Clinical Trials (OMERACT) ultrasound pediatric task force but the Pan American League of Associations for Rheumatology (PANLAR) US Pediatric Task Force is also working on validating MSKUS in children. In addition, several MSKUS courses for pediatric rheumatologists have been offered in Latin American countries; these will not only complement the scientific work pediatric-specific ultrasonography training, but also represents an essential component for the successful implementation of this technique into daily practice as well.

The joints in juvenile idiopathic arthritis

Abstract

Juvenile idiopathic arthritis is the most common rheumatic entity in childhood. Imaging has become an important supplement to the clinical assessment of children with JIA. Radiographs still play an important role in the workup, and long-term follow-up in children with JIA, but are not sensitive to findings in the early disease stage. Both ultrasound and MRI are more sensitive to inflammatory changes than clinical assessment alone. However, the differentiation between normal findings and pathology can be challenging, particularly in early disease. The objective of this review is to discuss the role of imaging in JIA, describe the typical findings on different modalities and highlight the challenges we face regarding the reliability and accuracy of the different methods for imaging the joints in children with JIA.

Key Points

• Imaging is an important supplement to the clinical examination in JIA.

• Ultrasound is more sensitive for detecting synovitis than clinical examination alone.

• MRI can depict all relevant structures in joint inflammation.

• The differentiation between normal variants and pathology is difficult in children.

Feasibility of diffusion-weighted magnetic resonance imaging in patients with juvenile idiopathic arthritis on 1.0-T open-bore MRI

OBJECTIVE

To evaluate the feasibility of non-invasive diffusion-weighted imaging (DWI) of the knee of children with juvenile idiopathic arthritis (JIA) and, further, to analyze the apparent diffusion coefficient (ADC) levels to distinguish synovium from effusion.

MATERIALS AND METHODS

Standard magnetic resonance imaging of the knee including post-contrast imaging was obtained in eight patients (mean age, 12 years 8 months, five females) using an open-bore magnetic resonance imaging system (1.0 T). In addition, axially acquired echo-planar DWI datasets (b-values 0, 50, and 600) were prospectively obtained and the diffusion images were post-processed into ADC50-600 maps. Two independent observers selected a region of interest (ROI) for both synovium and effusion using aligned post-contrast images as landmarks. Mann-Whitney U test was performed to compare ADC synovium and ADC effusion.

RESULTS

DWI was successfully obtained in all patients. When data of both observers was combined, ADC synovium was lower than ADC effusion in the ROI in seven out of eight patients (median, 1.92 × 10(-3) mm(2)/s vs. 2.40 × 10(-3) mm(2)/s, p = 0.006, respectively). Similar results were obtained when the two observers were analyzed separately (observer 1: p = 0.006, observer 2: p = 0.04).

CONCLUSIONS

In this pilot study, on a patient-friendly 1.0-T open-bore MRI, we demonstrated that DWI may potentially be a feasible non-invasive imaging technique in children with JIA. We could differentiate synovium from effusion in seven out of eight patients based on the ADC of synovium and effusion. However, to select synovium and effusion on DWI, post-contrast images were still a necessity.