Magnetic resonance imaging of temporomandibular joints in juvenile idiopathic arthritis

The reliability and validity of the juvenile idiopathic arthritis magnetic resonance scoring system for temporomandibular joints

In children with juvenile idiopathic arthritis (JIA), the temporomandibular joint (TMJ) can be involved. To prevent TMJ damage due to inflammation, early recognition is important, for which contrast-enhanced magnetic resonance imaging (MRI) is the gold standard. In this study, the interobserver reliability and construct validity of the Juvenile Idiopathic Arthritis Magnetic Resonance Scoring System for Temporomandibular Joints (JAMRIS-TMJ) was assessed. Two radiologists independently examined 38 MRIs using the JAMRIS-TMJ scoring system. Inter-observer reliability was assessed by Cohen's (weighted) kappa (κ), 95% confidence intervals (CIs) and absolute agreement (%). Construct validity was assessed by correlation between the JAMRIS-TMJ items and TMJ involvement, active maximum interincisal mouth opening (AMIO), and anterior maximum voluntary bite force (AMVBF). The interobserver reliability for the JAMRIS-TMJ items varied from poor to good (κ = 0.18-0.61). Joint enhancement had the highest reliability (κ = 0.61). Correlations were found between TMJ involvement, AMIO, and the JAMRIS-TMJ items, although variation between radiologists and TMJ side existed. No correlation was found between AMVBF and the JAMRIS-TMJ items for both radiologists. The strongest correlations were found between most of the JAMRIS-TMJ items and AMIO. Our findings support the utility of AMIO as a clinical measure of TMJ status in children with JIA.

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.

Temporomandibular joint involvement in patients with Juvenile Idiopathic Arthritis: comparison of ultrasonography and magnetic resonance imaging in assessing the periarticular space width

OBJECTIVES

This study aimed to compare the performance of Ultrasonography (US) and Magnetic Resonance Imaging (MRI) in assessing the Lateral Periarticular Space (LPAS) of Temporomandibular Joints (TMJs) in patients with Juvenile Idiopathic Arthritis (JIA).

METHODS

The LPAS width was evaluated in two different patient groups. In the JIA group, including 29 children (13 ± 2.8 years) with JIA, the LPAS width was measured with both MRI and US. In the healthy group, including 28 healthy children (12.6 ± 2.5 years), the LPAS width was measured only with US. Comparisons of LPAS width based on patient groups and TMJ contrast enhancement in MRI were evaluated by applying the Mann-Whitney U test. Correlation and agreement between MRI and US measurements in JIA group were tested using Spearman rank correlation and Bland-Altman method.

RESULTS

The LPAS width was significantly greater in the JIA group than in the healthy group. In the JIA group, the LPAS width was significantly greater in TMJs with moderate/severe enhancement than those with mild enhancement. A positive significant correlation between MRI and US measurements of LPAS width was found in the JIA group. In the same group, Bland-Altman method showed a good level of agreement between MRI and US measurements.

CONCLUSION

Although, US cannot replace MRI in the evaluation of TMJ in patients with JIA, US could be used as a supplementary imaging method to MRI in assessing the TMJ disease.

MRI of the temporomandibular joint in children with juvenile idiopathic arthritis: protocol and findings

Contrast-enhanced magnetic resonance imaging (MRI) is the technique of choice for diagnosis and monitoring of temporomandibular joint (TMJ) disorders in patients with juvenile idiopathic arthritis (JIA), as it is able to visualize both soft tissue and osteochondral changes. Approximately 40% of children with JIA develop inflammatory and chronic osteochondral changes observable on imaging, which if left untreated can lead to significant facial growth impairment, including facial asymmetry and retrognathia. MRI of the TMJ plays a paramount role in diagnosis and treatment monitoring in JIA since early signs of TMJ involvement are difficult to detect clinically and with physical examination. Findings of TMJ arthritis may be classified into acute and chronic domains. Early or acute manifestations include joint effusion, bone marrow edema, synovial thickening, and increased joint enhancement. With disease progression, there are characteristic osteochondral changes, including deformity of the mandibular condyle with shortening of the mandibular ramus, bone erosions, and disk abnormalities. In this pictorial essay, we describe a consensus MRI protocol for the study of the TMJ and illustrate the degree of normal and pathological MRI findings using currently available MRI scoring systems of the TMJ developed for JIA.

Does MRI Distinguish Juvenile Idiopathic Arthritis from Other Causes of Progressive TMJ Destruction?

PURPOSE

Similarities in initial presentations of temporomandibular joint (TMJ) involvement from juvenile idiopathic arthritis (JIA), idiopathic condylar resorption, and other forms of progressive TMJ destruction in children create diagnostic confusion. Treatment pathways, however, depend on determination of etiology. The purpose of this study was to compare TMJ magnetic resonance images (MRIs) of patients with joint degeneration localized to the TMJs to those with JIA and TMJ involvement.

METHODS

This is a retrospective cross-sectional study including subjects younger than 18 years that presented from February 2008 to October 2019 with clinical TMJ degeneration, a gadolinium-enhanced TMJ MRI and a negative pediatric rheumatologic workup ("non-JIA" group), and a series of age and sex-matched subjects with TMJ degeneration on gadolinium-enhanced MRI and JIA ("JIA group"). MRIs were evaluated in a blinded fashion by 1 pediatric radiologist. The primary outcome variable was the radiologist's accuracy in predicting study grouping, assessed in 1 randomly-selected joint per patient. Secondary outcome variables included MRI characteristics of inflammation, osseous damage and articular disc morphology. Independent samples t-tests, sensitivity/specificity, Fisher's exact and Mann-Whitney tests were computed as applicable, and P < .05 was considered significant.

RESULTS

The sample included 34 subjects: 16 non-JIA (75% female, age 13.9 ± 2.8 years) and 18 JIA (77% female, age 13.6 ± 2.8 years) (P ≥ .738). The radiologist correctly classified 64.7% of subjects as non-JIA or JIA (P = .078, sensitivity = 94.4%, specificity = 31.3%). Inflammatory and osseous findings were similar between groups (P ≥ .073). The disc was anteriorly displaced in 9 non-JIA and 0 JIA joints (P < .001, sensitivity = 100%, specificity = 100%) and flattened in 3 non-JIA and 14 JIA joints (P = .006, sensitivity = 38.9%, specificity = 90.6%).

CONCLUSION

Inflammatory and osseous findings on gadolinium-enhanced TMJ MRIs are insufficient to determine the etiology of progressive TMJ destruction. Disc characteristics, however, significantly differ between JIA and non-JIA etiologies and may be important in differentiating these conditions.

Magnetic resonance imaging assessment of juvenile idiopathic arthritis using OMERACT and EuroTMjoint classifications

This retrospective case-control study compared inflammatory and structural damage in the temporomandibular joint of patients with juvenile idiopathic arthritis (JIA) and its subtypes and healthy patients using the Outcome Measures in Rheumatology Clinical Trials (OMERACT) and EuroTMjoint classifications. Correlations between the scores of the two classifications and time of diagnosis were evaluated. Twenty-nine JIA patients and 48 age-matched healthy participants were examined. TMJ images on each side were considered individually. Oligoarticular and polyarticular subtypes were present in 44.8% and 55.2% of patients, respectively. The JIA group presented a higher frequency and more severe signs of inflammatory and structural changes (P < 0.05), except for effusion (P = 0.83). The polyarticular subtype showed a higher change intensity. The time of JIA diagnosis was not correlated with inflammatory and structural changes. Positive correlations between inflammation and bone deformity scores were observed for the EuroTMjoint classification (r = 0.462, P < 0.001; low correlation) and OMERACT classification (r = 0.737, P < 0.001; high correlation). Positive correlations between the OMERACT and EuroTMjoint classifications were found for inflammation score (r = 0.907, P < 0.001; very high correlation) and bone deformity score (r = 0.854, P < 0.001; high correlation). Both classifications showed a higher frequency and intensity of inflammation and bone deformity in JIA patients. The results of this study suggest that the appropriate management of inflammation may reduce the potential for structural damage to the TMJ.

Preliminary experience with black bone magnetic resonance imaging for morphometry of the mandible and visualisation of the facial skeleton

BACKGROUND

Children with orofacial deformity may require repeated imaging of the facial skeleton.

OBJECTIVE

To test the feasibility and accuracy of "black bone" magnetic resonance imaging (MRI) for assessing facial deformity in children.

MATERIALS AND METHODS

Three-dimensional (3-D) black bone gradient echo sequences (flip angle 5°, submillimetre spatial resolution) from 10 children (median age: 13 years, range: 2-16 years), who underwent MRI of the temporomandibular joints, were evaluated with multiplanar reconstruction and 3-D rendering tools. Intra- and inter-reader agreement was investigated for measuring the height of the mandibular ramus and condyle, basal length of the mandible, gonion angle and mandibular inclination angle by intraclass correlation coefficient (ICC) and Bland-Altman analysis. Absolute percentage error was calculated with the average of all measurements serving as reference.

RESULTS

Sixty linear and 40 angle measurements were obtained on reformatted multiplanar black bone images with excellent inter-reader agreement (ICC > 0.99, agreement bias < 1.4 mm/ < 1.5°) and small error (median absolute error < 3%). The black bone images required inversion of the signal intensity and removal of air before they could be processed with standard volume rendering tools. The diagnostic utility of 3-D views for assessing the facial skeleton was sufficient except for assessing dental relationship.

CONCLUSION

Morphometric measurements of the mandible can be obtained from black bone MRI with comparable inter-rater agreement to that reported for cone beam computed tomography (CT). With improvements of 3-D rendering techniques and software, black bone MRI may become a radiation-free alternative to CT in children with facial deformities.

The Temporomandibular Joint in Juvenile Idiopathic Arthritis

Patients with juvenile idiopathic arthritis (JIA) often have involvement of the temporomandibular joint (TMJ) during their disease course. Active arthritis of the TMJ remains difficult to assess. Clinical signs and symptoms alone are unreliable, and active TMJ arthritis needs confirmation by gadolinium-enhanced MRI. In recent years, changes in treatment approach have occurred. This article discusses the latest evidence on diagnosis and treatment of JIA-associated TMJ arthritis.

Juvenile idiopathic arthritis of the temporomandibular joint - no longer the forgotten joint

Juvenile idiopathic arthritis (JIA) of the temporomandibular joint (TMJ) is common in children, with an increasing awareness of the condition in all healthcare professionals. TMJ involvement presents a challenge in both diagnosis and treatment, as late presentation can still occur as the disease often develops asymptomatically. This can result in facial deformity and/or functional difficulties including obstructive sleep apnoea. Early diagnosis is therefore essential, requiring a high index of clinical suspicion coupled with the judicious use of gadolinium contrast magnetic resonance imaging (MRI). Long-term management is best provided by a multidisciplinary team as patients often need a combination of pharmacological management, surgical interventions, orthodontics, and psychological support. End stage deformity can be treated by different surgical options, each with their own risks and benefits, however recently there is increasing recognition for the role of total alloplastic TMJ replacement. This review focuses on the diagnosis and management of TMJ arthritis and aims to highlight the important role of maxillofacial surgeons in JIA treatment.

Discrete Choice Experiment on a Magnetic Resonance Imaging Scoring System for Temporomandibular Joints in Juvenile Idiopathic Arthritis

OBJECTIVE

To determine the relative importance weights of items and grades of a newly developed additive outcome measure called the juvenile idiopathic arthritis (JIA) magnetic resonance imaging (MRI) scoring system for temporomandibular joints (TMJ, JAMRIS-TMJ).

METHODS

An adaptive partial-profile discrete choice experiment (DCE) survey using the 1000Minds platform was independently completed by members of an expert group consisting of radiologists and non-radiologist clinicians to determine the group-averaged relative weights for JAMRIS-TMJ. Subsequently, an image-based vignette ranking exercise was done, during which experts individually rank-ordered 14 patient vignettes for disease severity while blinded to the weights and unrestricted to JAMRIS-TMJ assessment criteria. Validity of the weighted JAMRIS-TMJ was tested by comparing the consensus-graded, DCE-weighted JAMRIS-TMJ score of the vignettes with their unrestricted image-based ranks provided by the experts.

RESULTS

Nineteen experts completed the DCE survey and 21 completed the vignette ranking exercise. Synovial thickening and joint enhancement showed higher weights per raw score compared to bone marrow items and effusion in the inflammatory domain, while erosions and condylar flattening showed non-linear and higher weights compared to disk abnormalities in the damage domain. The weighted JAMRIS-TMJ score of the vignettes correlated highly with the ranks from the unrestricted comparison method, with median Spearman's rho of 0.92 (intra-quartile range: 0.87-0.95) for the inflammation and 0.93 (0.90-0.94) for the damage domain.

CONCLUSIONS

A DCE survey was used to quantify the importance weights of the items and grades of the JAMRIS-TMJ. The weighted score showed high convergent validity with an unrestricted, holistic vignette ranking method.

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.

Efficacy and safety of intraarticular corticosteroid injections in adolescents with juvenile idiopathic arthritis in the temporomandibular joint: a Norwegian 2-year prospective multicenter pilot study

BACKGROUND

Intraarticular corticosteroids (IACs) have been used to treat temporomandibular joint (TMJ) arthritis. However, prospective clinical studies with magnetic resonance imaging (MRI) scoring are lacking. The aim of this study was to examine efficacy and safety of a single IAC in the TMJ in adolescents with juvenile idiopathic arthritis (JIA) in a clinical setting.

METHODS

In this Norwegian prospective multicenter pilot study 15 patients with JIA (mostly persistent oligoarthritis or RF negative polyarthritis categories) and a clinically and MRI-verified diagnosis of TMJ arthritis were treated with IACs and followed for 2 years. Demographics, systemic medication, general disease activity and outcome measures were recorded including a pain-index score and maximal incisal opening (MIO). Inflammation and bone damage scores were assessed, using two recently published MRI scoring systems with masked radiological evaluation.

RESULTS

Among the 15 patients, 13 received a single IAC (5 bilateral), and 2 repeated IACs once unilaterally. Thus, the total number of IACs was 22. Median age was 15 years and the majority had an age not thought of as critical regarding mandibular growth retardation due to steroid injection. During the 2-year observation period systemic medication with disease modifying antirheumatic drugs (DMARDs) including biologics was initiated or adjusted in 10/15 (67%) patients. At the 2-months study visit after injection we observed a minimal improvement in MIO from median 44 (1st, 3rd quartiles; 36, 48) mm to 45 (43, 47) mm, p = 0.045 and decreased MRI mean additive inflammatory score from 4.4 ± 1.8 standard deviations (SD) to 3.4 ± 2.0, p = 0.040. From baseline to the 2-months follow-up pain improved in 6/11 patients but pain scores were not significantly improved. MRI-assessed damage increased in two patients with repeated IACs, and decreased in 3 patients but most of the patients were stable over the 2-year follow-up. Intra-rater repeatability of the MRI scoring system domains varied from poor to excellent.

CONCLUSIONS

In this pilot study of predominately single IACs to the TMJ in combination with systemic treatment we observed improvement in MRI-assessed inflammation, mostly stable condylar bone conditions and minimal clinical improvement in adolescents with JIA and TMJ arthritis. No severe side effects were seen.

Magnetic Resonance Imaging Followup of Temporomandibular Joint Inflammation, Deformation, and Mandibular Growth in Juvenile Idiopathic Arthritis Patients Receiving Systemic Treatment

OBJECTIVE

To investigate the course of temporomandibular joint (TMJ) inflammation, osseous deformation, and mandibular ramus growth in children with juvenile idiopathic arthritis (JIA) during systemic therapy.

METHODS

Longitudinal study of 38 consecutive patients with JIA (29 female, median age 9.0 yrs, interquartile range 6.2-10.7 yrs) receiving systemic therapy with TMJ involvement, with 2 TMJ magnetic resonance imaging (MRI) examinations ≥ 2 years apart and no TMJ corticosteroid injection. Clinical and MRI findings were compared between initial and followup examinations and between TMJ with and without active inflammation at baseline.

RESULTS

Over a median period of 3.6 years (range, 2.0-8.7 yrs), MRI grade of TMJ inflammation improved (p = 0.009) and overall osseous deformity tended to become less severe (p = 0.114). In TMJ with arthritis at baseline (46 TMJ), both the grades of inflammation (p < 0.001) and deformity (p = 0.011) improved. In TMJ with no arthritis at baseline (30 TMJ), the frequency and grade of condylar deformation remained stable. Mandibular ramus growth rates were not significantly different between TMJ with and without arthritis at baseline (1.3 mm/yr vs 1.5 mm/yr, p = 0.273), and were not correlated with the degree of inflammation at baseline or followup. The frequency of facial asymmetry tended to be lower at followup than at initial examination (24% vs 45%, p = 0.056).

CONCLUSION

Our results suggest that systemic treatment of TMJ arthritis in children with JIA decreases the degree of inflammation seen on MRI, preserves osseous TMJ morphology, and maintains normal mandibular ramus growth.

Temporomandibular joint damage in juvenile idiopathic arthritis: Diagnostic validity of diagnostic criteria for temporomandibular disorders

BACKGROUND

Diagnostic criteria reported in the expanded taxonomy for temporomandibular disorders include a standardised clinical examination and diagnosis (DC/TMD 3.B) of temporomandibular joint (TMJ) damage in patients with juvenile idiopathic arthritis (JIA); however, their validity is unknown.

OBJECTIVES

To assess the validity of DC/TMD 3.B for the identification of TMJ damage in JIA-patients, using magnetic resonance imaging (MRI) as gold standard, and to investigate the relation between clinical findings and TMJ damage.

METHODS

Fifty consecutive JIA patients (9-16 years) were recruited. DC/TMD 3.B were compared with TMJs MRI (100 TMJs) performed maximum at 1 month from the visit. The severity of TMJ damage was scored in four grades. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), logistic regression models with odds ratio of DC/TMD 3.B and clinical findings respect to MRI were calculated.

RESULTS

The DC/TMD 3.B were inadequate in the identification of TMJ damage (sensitivity = 0.15, specificity = 0.92, PPV = 0.85, NPV = 0.28, P = 0.350). Chin deviation and TMJ crepitus were associated with worse TMJ damage (P = 0.006; P = 0.034). Reduced mouth opening (OR = 3.91, P = 0.039) and chin deviation (OR = 13.7, P = 0.014) were associated with the presence of TMJ damage. Combining "pain" (history of pain, TMJ pain, pain during movements) and "function" (TMJ crepitus, reduced mouth opening, chin deviation) clinical findings, the sensitivity and the specificity were 0.88 and 0.54.

CONCLUSION

DC/TMD 3.B present a low sensitivity to diagnose TMJ damage. Chin deviation, reduced mouth opening and TMJ crepitus are associated with TMJ damage. We suggest combining "pain" and "function" findings for the evaluation of TMJ damage in JIA patients.

Temporomandibular joint magnetic resonance imaging findings in adolescents with anterior disk displacement compared to those with juvenile idiopathic arthritis

BACKGROUND

Deformation of the mandibular condyle can be associated with anterior disk displacement (ADD) or involvement of the temporomandibular joint (TMJ) by juvenile idiopathic arthritis (JIA). Diagnostic differentiation is critical for proper management.

OBJECTIVES

To compare morphology and inflammation between TMJs with ADD and JIA.

METHODS

Retrospective assessment of contrast-enhanced TMJ MRI in 18 adolescents (15 female, mean age 15.1 ± 1.9 years) with ADD and age- and gender-matched patients with JIA. Articular disk findings, inflammatory signs and osseous morphology were compared.

RESULTS

In the ADD group, 31 of 36 disks were displaced. In total, 28 of 31 displaced disks showed thickening of the bilaminar zone. In JIA patients, the disks were mainly flattened (19/36), centrally perforated (12/36) and/or anteriorly displaced (2/36). In total, 19 of 31 TMJs with ADD showed various degrees of inflammation, with joint effusion, synovial thickening and joint enhancement not significantly different from JIA patients. Osseous deformity was present in 27 of 31 TMJs with ADD, with frequent erosions in both groups (ADD 25/31; JIA 32/36, P = 0.55) but lower grades of condylar and temporal bone flattening than in JIA (P ≤ 0.001). Glenoid fossa depth was preserved in 28 of 31 joints with ADD and decreased in 26 of 36 joints with JIA (P < 0.0001). Mandibular ramus height was decreased in both groups.

CONCLUSION

In adolescents, inflammatory signs are common MRI findings in symptomatic TMJs with ADD and thus should not be considered diagnostic for JIA involvement. In this cohort, both entities had high rates of condylar deformity, while TMJs with ADD showed a better-preserved and often normal shape of the glenoid fossa.

Developing a reference MRI database for temporomandibular joints in healthy children and adolescents

BACKGROUND

Recognition of normal temporomandibular joints (TMJs) is essential to assess arthropathic changes. Few, if any, prior studies have evaluated the morphological appearance of growing TMJs by magnetic resonance (MR) examinations in the pediatric population.

OBJECTIVE

This study aimed to determine normative osseous appearance of growing TMJs according to age and gender, both qualitatively and quantitatively, concerning structural and bone marrow changes.

MATERIALS AND METHODS

From 1,036 MR scans screened, one joint was included from each of 157 patients (76% female; 2-18 years) presenting with at least one normal-appearing TMJ was included. Quantitatively, mandibular condyle was characterized by measuring the following: (i) head-neck angle, (ii) anteversion angle, (iii) condylar dimensions (mediolateral, craniocaudal and anteroposterior [AP]) and (iv) condylar volume. Furthermore, qualitative categorization of condylar shape, into one of three types, and condylar bone marrow type was performed.

RESULTS

The head-neck angle significantly correlated with age (bivariable regression β =0.60, P<0.001), indicating an increase of 1.6 degrees per year. Except for AP diameter of condyles, all other mandibular dimensions and condylar volume increased with age (β =0.20-0.59, P≤0.001-0.004). Significant age difference was observed among the different condylar shapes (P<0.001), indicating a change from rounded head without anterior tilt to rectangular head with anterior tilt. Lastly, mandibular condylar size, measured by volume and by AP and mediolateral dimensions, appeared larger in males.

CONCLUSION

The morphology of the mandibular condyles changes with age. During development, the shape of the condyles changes from round to rectangular in contour with the development of the anterior condylar tilt, as measured by the head-neck angle.

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 temporomandibular joint abnormalities in juvenile idiopathic arthritis with a focus on developing a magnetic resonance imaging protocol

Inflammation and damage in the temporomandibular joint (TMJ) often develop without clinical symptoms but can lead to severe facial growth abnormalities and impaired health-related quality of life, making early diagnosis of TMJ changes crucial to identify. Inflammatory and osteochondral changes detectable through magnetic resonance imaging (MRI) occur in TMJs of approximately 40% of children with juvenile idiopathic arthritis (JIA), and no other imaging modality or physical method of examination can reliably detect these changes. Therefore contrast-enhanced MRI is the diagnostic standard for diagnosis and interval monitoring of JIA. However the specific usage of MRI for TMJ arthritis is not standardized at present. There is a recognized need for a consensus effort toward standardization of an imaging protocol with required and optional sequences to improve detection of pathological changes and shorten study time. Such a consensus imaging protocol is important for providing maximum information with minimally necessary sequences in a way that allows inter-site comparison of results of clinical trials and improved clinical management. In this paper we describe the challenges of TMJ imaging and present expert-panel consensus suggestions for a standardized TMJ MRI protocol.

Temporomandibular joint arthritis in juvenile idiopathic arthritis, now what?

BACKGROUND

Arthritis involving the temporomandibular joint (TMJ) complicates 40 - 96% of cases of juvenile idiopathic arthritis (JIA), potentially leading to devastating changes to form and function. Optimal evaluation and management of this joint remains a matter of ongoing discussion.

METHODS

We performed a PubMed search for all articles with keywords "temporomandibular" and "arthritis", covering the dates 2002 through February 28, 2018. A separate PubMed search was performed for all articles with keywords "temporomandibular joint", "arthritis", and "treatment" covering the same dates.

FINDINGS

The TMJ is a particularly challenging joint to assess, both clinically and with imaging studies. Clinical assessment of the TMJ is hampered by the low sensitivity of joint pain as well as the absence of physical exam findings early in the disease process. As with all joints, plain radiography and computed tomography only detect arthritic sequelae. Additionally, there is mixed data on the sensitivity of ultrasound, leaving magnetic resonance imaging (MRI) as the optimal diagnostic modality. However, several recent studies have shown that non-arthritic children can have subtle findings on MRI consistent with TMJ arthritis, such as joint effusion and contrast enhancement. Consequently, there has been an intense effort to identify features that can be used to differentiate mild TMJ arthritis from normal TMJs, such as the ratio of the enhancement within the TMJ itself compared to the enhancement in surrounding musculature. With respect to treatment of TMJ arthritis, there is minimal prospective data on medical therapy of this complicated joint. Retrospective studies have suggested that the response to medical therapy of the TMJ may lag behind that of other joints, prompting use of intraarticular (IA) therapy. Although most studies have shown short-term effectiveness of corticosteroids, the long-term safety of this therapy on local growth as well as on the development of IA heterotopic bone have prompted recommendations to limit use of IA corticosteroids. Severe TMJ disease from JIA can also be managed non-operatively with splints in a growing child, as well as with surgery.

CONCLUSION

In this review, we summarize literature on the diagnosis and management of TMJ arthritis in JIA and suggest a diagnostic and therapeutic algorithm for children with refractory TMJ arthritis.

Toward Establishing a Standardized Magnetic Resonance Imaging Scoring System for Temporomandibular Joints in Juvenile Idiopathic Arthritis

OBJECTIVE

The temporomandibular joints (TMJs) are frequently affected in children with juvenile idiopathic arthritis (JIA). Early detection is challenging, as major variation is present in scoring TMJ pathology on magnetic resonance imaging (MRI). Consensus-driven development and validation of an MRI scoring system for TMJs has important clinical utility in timely improvement of diagnosis and serving as an outcome measure. We report on a multi-institutional collaboration toward developing a TMJ MRI scoring system for JIA.

METHODS

Seven readers independently assessed MRI scans from 21 patients (42 TMJs, from patients ages 6-16 years) using 3 existing MRI scoring systems from American, German, and Swiss institutions. Reliability scores, scoring system definitions, and items were discussed among 10 JIA experts through 2 rounds of Delphi surveys, nominal group voting, and subsequent consensus meetings to create a novel TMJ MRI scoring system.

RESULTS

Average-measure absolute agreement intraclass correlation coefficients (avICCs) for the total scores of all 3 scoring systems were highly reliable at 0.96 each. Osteochondral items showed higher reliability than inflammatory items. An additive system was deemed preferable for assessing minor joint changes over time. Eight items were considered sufficiently reliable and/or important for integration into the consensus scoring system: bone marrow edema and enhancement (avICC 0.57-0.61, smallest detectable difference [SDD] ± 45-63% prior to redefining), condylar flattening (avICC 0.95-0.96, SDD ± 23-28%), effusions (avICC 0.85-0.88, SDD ± 25-26%), erosions (avICC 0.94, SDD ± 20%), synovial enhancement and thickening (previously combined, avICC 0.90-0.91, SDD ± 33%), and disk abnormalities (avICC 0.90, SDD ± 19%).

CONCLUSION

A novel TMJ MRI scoring system was developed by consensus. Further iterative refinements and reliability testing are warranted in upcoming studies.

Temporomandibular joint atlas for detection and grading of juvenile idiopathic arthritis involvement by magnetic resonance imaging

Contrast-enhanced magnetic resonance imaging (MRI) is considered the diagnostic standard for identifying involvement of the temporomandibular joint by juvenile idiopathic arthritis. Early or active arthritis is shown as bone marrow oedema, joint effusion, synovial thickening and increased joint enhancement. Subsequent joint damage includes characteristic deformity of the mandibular condyle, bone erosion, disk abnormalities and short mandibular ramus due to impaired growth. In this pictorial essay, we illustrate normal MRI findings and growth-related changes of the temporomandibular joint in children. The rationale and practical application of semiquantitative MRI assessment of joint inflammation and damage are discussed and presented. This atlas can serve as a reference for grading temporomandibular joint arthritis according to the scoring systems proposed by working groups of OMERACT (Outcome Measures in Rheumatology and Clinical Trials) and the EuroTMjoint research network. Systematic assessment of the level of inflammation, degree of osteochondral deformation, and growth of the mandibular ramus by MRI may aid in monitoring the course of temporomandibular joint arthritis and evaluating treatment options.

Qualitative and semi-quantitative assessment of temporomandibular joint MRI protocols for juvenile idiopathic arthritis at 1.5 and 3.0T

OBJECTIVE

Temporomandibular joints (TMJs) frequently develop silent inflammatory and osteochondral changes in children with juvenile idiopathic arthritis. Data-driven recommendations for TMJ imaging protocol are needed to reduce measurement error and scanning time. This study compares the impact of different protocols, imaging coils, and magnet strength on the reliability of image assessment and the subjective quality of images.

MATERIALS AND METHODS

Three groups of bilateral TMJ MR studies were retrospectively collected from two institutions, including 24 1.5T and 19 3.0T studies using dedicated TMJ surface coils, and 23 1.5T studies with head coil. Post-contrast sequences were re-compiled from the full protocol to create minimum protocol studies for the three groups. Two radiologists and two non-radiologists first scored the three minimum protocol images according to pre-specified definitions, then scored the full protocol images. Minimum-to-full protocol agreement, inter-reader agreement, and subjective item visibility scores were assessed.

RESULTS

With dedicated TMJ dual surface coils, minimum-vs-full protocol agreement was moderate to good (0.5-0.8 intraclass correlation coefficients or kappa) for most items, and was not influenced by the magnet strength. Inter-reader reliability was more significantly influenced by the imaging coil and reader's training background than by protocol length or magnet strength differences. Sagittal and coronal planes weighted on PD, T2 Fat Suppressed and T1 Fat Suppressed -postcontrast adequately visualized all the different features, whereas the axial plane was more limited to visualizing synovium.

CONCLUSION

Inter-reader reliability and qualitative measure of image quality improved more consistently with the coil offering the higher resolution, rather than increased magnet strength.