The many shades of enhancement: timing of post-gadolinium images strongly influences the scoring of juvenile idiopathic arthritis wrist involvement on MRI

Imaging of Juvenile Idiopathic Arthritis

MRI, ultrasound, and conventional radiography each play distinct roles in the evaluation of juvenile idiopathic arthritis (JIA), with MRI being the preferred imaging modality of choice for assessing both inflammatory and destructive changes. These various imaging modalities provide valuable insights into JIA in pediatric patients. However, challenges persist in terms of achieving precision, ensuring validity, and distinguishing between pathologic findings and normal anatomic variations. Establishing normal reference values and implementing scoring systems can aid in the precise evaluation of disease activity and provide information to assist treatment decisions for children with JIA. Ongoing advancements in imaging techniques and standardization initiatives aim to bolster the accuracy of JIA diagnosis and assessment, ultimately leading to enhanced patient care and treatment outcomes.

Developing standards for MRI evaluation of joints in children with juvenile idiopathic arthritis utilizing the temporomandibular joint as a model

The treatment of a patient with juvenile idiopathic arthritis (JIA) is best monitored with standardized and validated tools to measure joint changes over time. Treatment approaches are best indicated if the clinicians are aware of the structural status of the joint at a given time, especially in anatomically deep joints for which clinical assessment is limited. Magnetic resonance imaging (MRI) is of utmost importance for assessment of deep joints and extra-articular soft tissue of the entire body for which ultrasound may be suboptimal. Because the distinction between pathologic and physiologic joint changes on MRI is key for proper diagnosis and treatment of patients with arthropathies, a comprehensive standardized approach is needed to effectively measure outcomes of growing joints of children with JIA. Such an approach is essential for both clinical assessment and to conduct clinical trials in patients with JIA treated in different centers around the world. To meet this need, several international imaging collaborative research groups have been developing MRI scales over the past years, including the MRI in JIA (JAMRI) special interest group within the Outcome Measures in Rheumatology (OMERACT) research network. This manuscript reviews the efforts of the OMERACT JAMRI working group to generate and validate pediatric MRI scoring systems for different joints in children with JIA that can have ubiquitous utilization anywhere in the world. In particular, it describes the different steps of development and validation of an MRI scale using the TMJ as a model.

Fluid-attenuated inversion-recovery sequence with fat suppression as an alternative to contrast-enhanced MRI in pediatric synovitis

BACKGROUND

Non-contrast magnetic resonance imaging (MRI) fluid-attenuated inversion-recovery sequence (FLAIR) with fat suppression (FS) has not been validated in children.

OBJECTIVE

Compare FLAIR to T1-weighted post contrast (T1CE) in the detection of knee synovitis.

METHODS AND MATERIALS

Institutional review board (IRB) waived consent. Children who underwent T1CE and FLAIR sequences of the knee on a 3-T magnet from April 2021 to December 2021 were included. Two pediatric radiologists assessed axial FLAIR and T1CE images for synovitis and synovial thickness. Reliability and agreement were assessed. Sensitivities, specificities, and accuracy were calculated for FLAIR using T1CE as reference standard.

RESULTS

In total, 42 knees (39 patients) were assessed (median age 12.9 years (2.3-17.8 years); 62% male, 38% female). Readers judged 20/42 (48%) knees to have synovitis. Sensitivity of FLAIR for reader 1 was 79% (19/24; 95% CI 0.58, 0.93) and 84% (16/19; 95% CI 0.60, 0.97) for reader 2. Specificity of FLAIR for reader 1 was 94% (17/18; 95% CI 0.73, 1) and 83% (19/23; 95% CI 0.61, 0.95) for reader 2. Accuracy for readers 1 and 2 was 86% (36/42; 95% CI 0.71, 0.95) and 83% (35/42; 95% CI 0.69, 0.93), respectively. Inter-reader reliability was good (0.75-0.90) for synovial measurements for FLAIR (ICC = 0.80; 95% CI 0.71, 0.86) and moderate for T1 CE (ICC = 0.62 (95% CI 0.48, 0.73)).

CONCLUSION

FLAIR FS depicts synovium in the pediatric knee with similar reliability to T1 CE and may be an acceptable alternative to contrast in the initial diagnosis of synovitis.

A novel magnetic resonance imaging scoring system for active and chronic changes in children and adolescents with juvenile idiopathic arthritis of the hip

BACKGROUND

Hip involvement predicts severe disease in juvenile idiopathic arthritis (JIA) and is accurately assessed by MRI. However, a child-specific hip MRI scoring system has not been validated.

OBJECTIVE

To test the intra- and interobserver agreement of several MRI markers for active and chronic hip changes in children and young adults with JIA and to examine the precision of measurements commonly used for the assessment of growth abnormalities.

MATERIALS AND METHODS

Hip MRIs from 60 consecutive children, adolescents and young adults with JIA were scored independently by two sets of radiologists. One set scored the same MRIs twice. Features of active and chronic changes, growth abnormalities and secondary post-inflammatory changes were scored. We used kappa statistics to analyze inter- and intraobserver agreement for categorical variables and a Bland-Altman approach to test the precision of continuous variables.

RESULTS

Among active changes, there was good intra- and interobserver agreement for grading overall inflammation (kappa 0.6-0.7). Synovial enhancement showed a good intraobserver agreement (kappa 0.7-0.8), while the interobserver agreement was moderate (kappa 0.4-0.5). Regarding acetabular erosions on a 0-3 scale, the intraobserver agreement was 0.6 for the right hip and 0.7 for the left hip, while the interobserver agreement was 0.6 for both hips. Measurements of joint space width, caput-collum-diaphyseal angle, femoral neck-head length, femoral width and trochanteric distance were imprecise.

CONCLUSION

We identified a set of MRI markers for active and chronic changes in JIA and suggest that the more robust markers be included in future studies addressing clinical validity and long-term patient outcomes.

Juvenile idiopathic arthritis of the knee: is contrast needed to score disease activity when using an augmented MRI protocol comprising PD-weighted sequences?

Objective

To compare unenhanced versus enhanced knee joint magnetic resonance imaging (MRI) to assess disease activity of juvenile idiopathic arthritis (JIA).

Methods

Fifty-three knee joint MRI examinations were performed on a 3-Tesla system in 27 patients (age: 11.40 ± 3.61 years; 21 females, 6 males). MRI protocols comprised PD-weighted sequences in addition to the widely used standard protocol. JIA subgroups comprised oligoarticular arthritis (n = 16), extended oligoarthritis (n = 6), rheumatoid factor-negative polyarticular arthritis (n = 3), enthesitis-related arthritis (n = 1), and psoriatic arthritis (n = 1). MR images were retrospectively analyzed by 3 experienced radiologists in two readings, using JAMRIS (juvenile arthritis MRI scoring) system and a modified IPSG (international prophylaxis study group) classification. In the first reading session, only unenhanced MR images were evaluated. In a second reading session, all images before and after contrast medium application were included. In order to avoid bias, an interval of at least 2 weeks was set between the two readings. The clinical JADAS10 (juvenile arthritis disease activity score) was calculated including clinical assessment and laboratory workup and correlated with MRI scores. Statistical analysis comprised Pearson’s correlation for correlating two scoring results of unenhanced and the enhanced MRI, intra-class correlation coefficient (ICC) for inter- and intra-reader agreement. Diagnostic accuracy was calculated using ROC (receiver operating characteristics) curve analysis.

Results

Inter-reader agreement determined by ICC for unenhanced and enhanced MRI scores for IPSG was moderate (0.65, 95% CI 0.51–0.76, and 0.62, 95% CI 0.48–0.75) and high for JAMRIS (0.83, 95% CI 0.75–0.89, and 0.82, 95% CI 0.74–0.89). Intra-reader agreement was good to very good for JAMRIS (0.85 95% CI 0.81–0.88, 0.87 95% CI 0.83–0.89 and 0.96 95% CI 0.92–0.98) and IPSG (0.76 95% CI 0.62–0.86, 0.86 95% CI 0.77–0.92 and 0.92 95% CI 0.86–0.96). Scores of unenhanced MRI correlated with contrast-enhanced MRI: JAMRIS (r = 0.97, R2 = 0.93, p < 0.01), modified IPSG (r = 0.95, R2 = 0.91, p < 0.01). When using JADAS10 as a reference standard, moderate accuracy for both unenhanced and enhanced MRI scores was noted: JAMRIS (AUC = 0.68, 95% CI 0.51–0.85, and AUC = 0.66, 95% 0.49–0.82), IPSG score (AUC = 0.68, 95% 0.50–0.86, and AUC = 0.61, 95% 0.41–0.81).

Conclusions

Our results suggest that contrast agent application could be omitted in JIA patients with an augmented knee MRI protocol comprising PD-weighted sequence.

Key Points

• Unenhanced MRI can detect disease activity of the knee joint in patients with JIA with equally high accuracy compared to contrast-enhanced MRI.

• The intra- and inter-reader agreement was high for unenhanced and enhanced MRI JAMRIS scores, which indicate relatively good applicability of the scoring system, even for less experienced readers.

• When using the clinical JADAS10 as a reference standard for the detection of disease activity, moderate accuracy for both unenhanced and enhanced MRI scores, both JAMRIS and IPSG, was noted, which might be caused by the fact that the majority of patients had either no or minimal clinical disease activity.

[Spondyloarthritis in childhood and adulthood]

Axial spondylarthritis in adulthood (SpAA) is frequently initially manifested as a sacroiliitis, whereas this not true for enthesitis-related arthritis (EAA), which begins in childhood and adolescence. Classically, EAA begins with peripheral arthritis and only a part transitions into a juvenile SpA (jSpA) or SpAA. The criteria used for classification of SpAA and EAA are currently being validated and revised. For the first time imaging is included for EAA. For both diseases nonsteroidal anti-inflammatory drugs (NSAID) are initially used therapeutically, followed by biologicals or synthetic targeted disease-modifying drugs in refractory courses. Steroids should be avoided in long-term treatment. For optimal transition and further care in adulthood, a close cooperation between internistic and pediatric rheumatologists is necessary.

Magnetic resonance imaging findings in the normal pediatric sacroiliac joint space that can simulate disease

BACKGROUND

Magnetic resonance imaging (MRI) features of active sacroiliac joint inflammation include joint space fluid and enhancement, but it is unclear to what extent these are present in normal children.

OBJECTIVE

To describe normal MRI appearances of pediatric sacroiliac joint spaces in boys and girls of varying ages.

MATERIALS AND METHODS

In this ethics-approved prospective study, 251 children (119 boys, 132 girls; mean age: 12.4 years, range: 6.1-18.0 years), had both oblique-coronal T1-weighted and short tau inversion recovery (STIR) sacroiliac joint MRI. Of these, 127 were imaged for other reasons and had asymptomatic sacroiliac joints ("normal cohort") while 124 had low back pain with no features of sacroiliitis on initial clinical MRI review ("low-back-pain cohort"). Post-gadolinium T1-weighted sequences were available in 16/127 normal and 124/124 low-back-pain subjects. Three experienced radiologists scored high signal in the sacroiliac joint space on STIR (score 0=absent; 1=high signal compared to normal bone marrow present anywhere in the joint but not as bright as fluid [compared to vessels, cerebrospinal fluid]; 2=definite fluid signal in part of the joint; 3=definite fluid signal, entire vertical height, majority of slices) and, when available, joint space post-contrast enhancement (0=no high signal/enhancement; 1=thin, symmetrical, mildly increased linear high signal present in the joint space; 2=focal, thick or intense enhancement). Associations between joint signal scores, age, gender and sacral apophyseal closure were analysed.

RESULTS

Increased signal on STIR (score 1-3) was present in 74.7% of pediatric sacroiliac joint spaces, as intense as fluid in 18.4%. There was no significant difference in proportion by gender, side or cohort, but girls showed peak signal earlier than boys (10 years old vs. 12 years old, respectively). On post-gadolinium T1-weighted sequences, a thin rim of increased signal was nearly universally seen in sacroiliac joint spaces without focal, intense or thick post-contrast enhancement.

CONCLUSION

Sacroiliac joint spaces of most children demonstrate mildly increased signal on STIR, compared to normal bone marrow, and thin rim-like enhancement on post-contrast T1 images, likely related to cartilage. These findings should not be confused with sacroiliitis.

Comparison of contrast-enhanced MRI features of the (teno)synovium in the wrist of patients with juvenile idiopathic arthritis and pediatric controls

To directly compare and describe the differences between juvenile idiopathic arthritis (JIA) patients and pediatric controls regarding features of the synovial and tenosynovial membrane on contrast-enhanced magnetic resonance imaging (MRI) of the wrist. T1-weighted contrast-enhanced MRI scans of 25 JIA patients with clinically active wrist arthritis and 25 children without a history of joint complaints nor any clinical signs of joint inflammation were evaluated by two readers blinded to clinical data. The synovium was scored at five anatomical sites based on thickening of the synovium (0–3 scale) and synovial enhancement (0–2 scale). Thickening and/or enhancement of the tenosynovium was scored at four anatomical sites using a 0–3 scale. Significantly higher scores for synovial thickening (median 4 vs. 1, p < 0.001) and synovial enhancement (median 4 vs. 1, p < 0.001) are found in the wrist of JIA patients as compared to controls. JIA patients experienced the highest synovial scores at the mid-/inter-carpal, 2nd –5th carpometacarpal, and radiocarpal joints. No significant difference in tenosynovial scores is found between both groups (median 0 vs. 0, p = 0.220). This study highlights the higher synovial thickening/enhancement scores on contrast-enhanced MRI of the wrist in JIA patients compared to pediatric controls. Tenosynovial thickening and/or enhancement was rarely present in both groups. In JIA patients, synovial thickening and enhancement were particularly present at three anatomical sites. These results substantially support rheumatologists and radiologists when navigating through MRI of the wrist in search for JIA disease activity.

Consensus-driven conceptual development of a standardized whole body-MRI scoring system for assessment of disease activity in juvenile idiopathic arthritis: MRI in JIA OMERACT working group

OBJECTIVES

Whole body-MRI is helpful in directing diagnostic and treatment approaches, and as a research outcome measure. We describe our initial consensus-driven phase towards developing a whole body-MRI scoring system for juvenile idiopathic arthritis.

METHODS

An iterative approach using three rounds of anonymous Delphi surveys followed by a consensus meeting was used to draft the structure of the whole body-MRI scoring system, including the relevant anatomic joints and entheses for assessment, diagnostic item selection, definition and grading, and selection of appropriate MRI planes and sequences. The surveys were completed independently by an international expert group consisting of pediatric radiologists and rheumatologists.

RESULTS

Twenty-two experts participated in at least one of three rounds of Delphi surveys and a concluding consensus meeting. A first iteration scoring system was developed which ultimately included the assessment of 100 peripheral, 23 chest, and 76 axial joints, and 64 entheses, with 2-4 diagnostic items graded in each of the items, using binary (presence/absence) and 2-3-level ordinal scores. Recommendations on anatomic MRI planes and sequences were specified as the minimally necessary imaging protocol for the scoring system.

CONCLUSION

A novel whole body-MRI scoring system for juvenile idiopathic arthritis was developed by consensus among members of MRI in JIA OMERACT working group. Further iterative refinements, reliability testing, and responsiveness are warranted in upcoming studies.

Toward Developing a Semiquantitative Whole Body-MRI Scoring for Juvenile Idiopathic Arthritis: Critical Appraisal of the State of the Art, Challenges, and Opportunities

With powerful new therapies available for management of juvenile idiopathic arthritis (JIA), early diagnosis leading to appropriate treatment may prevent long-term structural joint damage. Although magnetic resonance imaging (MRI) is typically used to assess individual body parts, indications for whole body (WB) MRI are increasing. Its utility as a diagnostic and monitoring tool has already been widely investigated in adult rheumatology patients, but less so in pediatric rheumatologic patients. This paper is a comprehensive review of scoring systems and a proposal for the conceptual development of a WB-MRI scoring system for the evaluation of JIA. In this review we identify, summarize, and critically appraise the available literature on the use of WB-MRI in inflammatory arthritis, addressing relevant considerations on components of a classification system that can lead to the development of a future pediatric WB-MRI scoring system for use in children with JIA. We also discuss advantages and challenges of developing such a WB-MRI scoring system for assessment of JIA and outline next steps toward the conceptual development of this scoring system.

Current status of MR imaging of juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common chronic arthropathy in the pediatric population. Although the diagnosis is essentially clinical for many affected joints, MR imaging has become an important tool for the assessment of joints that are difficult to evaluate clinically, such as temporomandibular and sacroiliac joints, and for screening of inflammatory changes in the entire body by whole body MRI (WBMRI) assessment. The utilization of MR imaging is challenging in the pediatric population given the need for discrimination between pathological and physiological changes in the growing skeleton. Several multicentric multidisciplinary organizations have made major efforts over the past decades to standardize, quantify, and validate scoring systems to measure joint changes both cross-sectionally and longitudinally according to rigorous methodological standards. In this paper, we (1) discuss current trends for the diagnosis and management of JIA, (2) review challenges for detecting real pathological changes in growing joints, (3) summarize the current status of standardization of MRI protocols for data acquisition and the quantification of joint pathology in JIA by means of scoring systems, and (4) outline novel MR imaging techniques for the evaluation of anatomy and function of joints in JIA. Optimizing the role of MRI as a robust biomarker and outcome measure remains a priority of future research in this field.

Imaging assessment of children presenting with suspected or known juvenile idiopathic arthritis: ESSR-ESPR points to consider

Juvenile idiopathic arthritis (JIA) is the most common paediatric rheumatic disease. It represents a group of heterogenous inflammatory disorders with unknown origin and is a diagnosis of exclusion in which imaging plays an important role. JIA is defined as arthritis of one or more joints that begins before the age of 16 years, persists for more than 6 weeks and is of unknown aetiology and pathophysiology. The clinical goal is early suppression of inflammation to prevent irreversible joint damage which has shifted the emphasis from detecting established joint damage to proactively detecting inflammatory change. This drives the need for imaging techniques that are more sensitive than conventional radiography in the evaluation of inflammatory processes as well as early osteochondral change. Physical examination has limited reliability, even if performed by an experienced clinician, emphasising the importance of imaging to aid in clinical decision-making. On behalf of the European Society of Musculoskeletal Radiology (ESSR) arthritis subcommittee and the European Society of Paediatric Radiology (ESPR) musculoskeletal imaging taskforce, based on literature review and/or expert opinion, we discuss paediatric-specific imaging characteristics of the most commonly involved, in literature best documented and clinically important joints in JIA, namely the temporomandibular joints (TMJs), spine, sacroiliac (SI) joints, wrists, hips and knees, followed by a clinically applicable point to consider for each joint. We will also touch upon controversies in the current literature that remain to be resolved with ongoing research. KEY POINTS: • Juvenile idiopathic arthritis (JIA) is the most common chronic paediatric rheumatic disease and, in JIA imaging, is increasingly important to aid in clinical decision-making. • Conventional radiographs have a lower sensitivity and specificity for detection of disease activity and early destructive change, as compared to MRI or ultrasound. Nonetheless, radiography remains important, particularly in narrowing the differential diagnosis and evaluating growth disturbances. • Mainly in peripheral joints, ultrasound can be helpful for assessment of inflammation and guiding joint injections. In JIA, MRI is the most validated technique. MRI should be considered as the modality of choice to assess the axial skeleton or where the clinical presentation overlaps with JIA.

Exploring contrast-enhanced MRI findings of the clinically non-inflamed symptomatic pediatric wrist

BACKGROUND

Knowledge of the synovial and tenosynovial appearance of the clinically non-arthritic symptomatic juvenile wrist using contrast-enhanced magnetic resonance imaging (MRI) is sparse.

OBJECTIVES

To analyze contrast-enhanced MRI findings of the clinically non-inflamed symptomatic pediatric wrist, focusing on the enhancing synovial and tenosynovial membrane. To evaluate the coexistent presence of (teno)synovial enhancement, joint fluid, bony depressions and medullary changes suggestive of bone marrow edema.

MATERIALS AND METHODS

We included 20 children (15 girls; age range: 7.5-17.6 years) who underwent contrast-enhanced MRI of the wrist, based on initial clinical indication, and eventually turned out to be unaffected by arthritic or orthopedic disorders. Various imaging characteristics of the synovium, tenosynovium, joint fluid, bone tissue and bone marrow were evaluated using existing MRI scoring systems.

RESULTS

In 3/20 (15%) children, mild or moderate-severe synovial enhancement was observed and 2/20 (10%) children showed mild tenosynovial enhancement/thickening. Joint fluid (11/20 children; 55%), bony depressions (20/20 children; 100%) and medullary changes suggestive of bone marrow edema (6/20; 30%) were found in a substantial percentage of children. The most frequently observed combination of coexisting imaging characteristics was bony depressions with ≥2 mm joint fluid, which was found in 7/20 (35%) children. Simultaneous presence of synovial and tenosynovial enhancement/thickening, bony depressions and medullary changes suggestive of bone marrow edema was observed in one child.

CONCLUSION

Several juvenile idiopathic arthritis-relevant MRI characteristics can be observed in the clinically non-inflamed symptomatic pediatric wrist.

Review article: the differential diagnosis of bone marrow edema on wrist MRI

There is a large variety of conditions that can result in 'bone marrow edema' or 'bone marrow lesions' (BML) in the wrist on magnetic resonance imaging (MRI). The combination of clinical history and the distribution of the BML can serve as a valuable clue to a specific diagnosis. This article illustrates the different patterns of BML in the wrist to serve as a useful guide when reviewing wrist MRI studies. Imaging artefacts will also be briefly covered.

Prolonged time between intravenous contrast administration and image acquisition results in increased synovial thickness at magnetic resonance imaging in patients with juvenile idiopathic arthritis

BACKGROUND

Post-contrast synovial thickness measurement is necessary for scoring disease activity in juvenile idiopathic arthritis (JIA). However, the timing of post-contrast sequences varies widely among institutions. This variation in timing could influence thickness measurements.

OBJECTIVE

To measure thickness of the synovial membrane on early and late post-contrast knee magnetic resonance (MR) images of patients with JIA.

MATERIALS AND METHODS

Dynamic contrast-enhanced T1-weighted knee MR images of 53 children with JIA with current or past knee arthritis were used to study synovial thickness at time point 1 (about 1 min) and time point 2 (about 5 min after contrast administration). Two experienced readers, who were blinded for the time point, independently measured synovial thickness at a predefined, marked location in the patellofemoral compartment on randomized images. Synovial thickness at the two time points was compared using the Wilcoxon signed rank test. Repeatibility of the synovial thickness measurements was studied using intraclass correlation coefficients and Bland-Altman plots.

RESULTS

Median synovial thickness of the 53 patients (median age: 13.5 years, 59% female) increased with prolonged post-contrast interval with a synovial thickness of 1.4 mm at time point 1 and a synovial thickness of 1.5 mm at time point 2 (P<0.001). Repeated synovial thickness measurements showed an intraclass correlation coefficient (ICC) of 0.75, P<0.05 for time point 1 and an ICC of 0.91, P<0.05 for time point 2.

CONCLUSION

Post-contrast synovial membrane thickness measurements are time-dependent. Therefore, standardization of post-contrast image acquisition timing is important to achieve consistent grading of synovial inflammation.

The role of imaging in juvenile idiopathic arthritis

INTRODUCTION

The prognosis of juvenile idiopathic arthritis (JIA) has changed dramatically due to the availability of novel drugs. Prompt diagnosis and treatment are essential to prevent permanent joint damage. As a result, methods to improve JIA diagnosis and prognosis are of high priority to tailor treatment strategies and maximize their efficacy. Musculoskeletal ultrasound and magnetic resonance imaging are more sensitive than clinical examination and radiography in the detection of joint involvement and might play a substantial role to optimize the management of JIA. Areas covered: This review compiles an inventory of potential uses of imaging studies in the modern practice of pediatric rheumatology, together with a critical analysis of the major challenges that are still to be addressed. Imaging appearance of normal growth-related changes of the musculoskeletal system will be discussed. Expert commentary: Knowledge of the evolving patterns of skeletal maturity is paramount to define pathological findings and avoid misinterpretations. Establishing a novel radiological algorithm for a rational use of imaging in JIA is of high priority to allow a speedier integration of imaging into the clinical workflow and decision-making process.

Imaging of the hip in juvenile idiopathic arthritis

Hip involvement is common and estimated to occur in approximately 35-63% of children with juvenile idiopathic arthritis (JIA). It is more prevalent in the aggressive systemic subtypes, with irreversible changes occurring as early as within 5 years of diagnosis. Whilst clinical parameters and joint examination can be useful for assessing disease severity, subclinical disease is known to exist and delayed treatment may herald a lifetime of disability and pain. Early recognition of JIA changes is therefore crucial in determining treatment options. Validated scoring systems in the radiologic assessment of the hip for clinical drug trials may inform treatment outcomes, although robust tools for analysis are still lacking. This review article details the modalities utilised for imaging the hip in children with JIA with particular efforts focused upon reliability and validity in their assessment of joint disease. We conclude with a short literature review on the potential future techniques being developed for hip joint imaging in JIA.

Current status of wrist imaging in juvenile idiopathic arthritis

Wrist involvement occurs in about one-quarter of patients diagnosed with juvenile idiopathic arthritis (JIA), increasing to 40% 5 years after diagnosis. The imaging appearances, both for active inflammation and permanent change, differ from those seen in adult rheumatoid arthritis; therefore, a child-specific approach is crucial for correct assessment. In this review article, we provide an update on the current status for imaging wrist JIA, with a focus on evidence-based practice.

Defining the normal appearance of the temporomandibular joints by magnetic resonance imaging with contrast: a comparative study of children with and without juvenile idiopathic arthritis

BACKGROUND

Up to 80% of children with juvenile idiopathic arthritis (JIA) develop arthritis involving their temporomandibular joint (TMJ). Recent studies have questioned the sensitivity of an abnormal MRI in the diagnosis of active arthritis.

METHODS

122 children without arthritis undergoing contrast MRI of the head were prospectively consented to undergo a simultaneous contrast MRI of their TMJs. As a comparison point, the initial MRI of the TMJ of 35 newly diagnosed children with JIA were retrospectively scored. The presence and size of effusion and contrast enhancement were measured in the left TMJ in all subjects.

RESULTS

62/122 (51%) controls compared to only 10/35 JIA (29%) patients had an effusion (p = 0.022). Contrast enhancement was present in ≥97% of both groups, although the size of the enhancement was, on average, 0.2 mm larger in controls (1.1 ± 0.24 vs 0.88 ± 0.27 mm, p <  0.001). Among JIA patients, the size of the enhancement correlated inversely with disease duration (r = - 0.475, p = 0.005). Chronic changes were present in none of the controls versus 2/35 (5.5%) of the JIA patients (p = 0.049).

CONCLUSION

Findings consistent with minimally active TMJ arthritis appear to be equally likely in children with JIA as compared to non-inflamed controls, while this and other studies confirm that chronic changes are specific to JIA. Thus, small amounts of effusion or contrast enhancement, in the absence of chronic changes, should be interpreted with caution.

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.

Contrast-enhanced MRI findings of the knee in healthy children; establishing normal values

OBJECTIVES

To define normative standards for the knee in healthy children using contrast-enhanced MRI, focusing on normal synovial membrane thickness. Secondly, presence of joint fluid and bone marrow oedema was evaluated.

METHODS

For this study, children without disorders potentially resulting in (accompanying) arthritis were included. Patients underwent clinical assessments, followed by contrast-enhanced MRI. MRI features were evaluated in consensus using the Juvenile Arthritis MRI Scoring (JAMRIS) system. Additionally, the presence of joint fluid was evaluated. No cartilage lesions or bone abnormalities were observed.

RESULTS

We included 57 healthy children. The overall mean thickness of the normal synovial membrane was 0.4 mm (min-max; 0.0-1.8mm). The synovium was thickest around the cruciate ligaments and retropatellar and suprapatellar regions. The mean overall diameter of the largest pocket of joint fluid was 2.8 mm (min-max; 0.9-8.0mm). Bone marrow changes were observed in three children (all in the apex patellae).

CONCLUSIONS

The normal synovial membrane was maximally 1.8 mm thick, indicating that the JAMRIS cut-off value of 2 mm can be considered a valid measure for evaluating synovial hypertrophy. Some joint fluid and bone marrow changes suggestive of bone marrow oedema in the apex patellae can be seen in healthy children.

KEY POINTS

• Knowledge on the normal synovial appearance using contrast-enhanced MR is lacking. • In healthy children, normal synovial membrane is maximally 1.8 mm thick. • Normal synovium is thickest around the cruciate ligaments, retropatellar and suprapatellar. • Bone marrow oedema in the apex patellae is seen in healthy children.