MRI in juvenile idiopathic arthritis and juvenile dermatomyositis

Ankle Magnetic Resonance Imaging in Juvenile Idiopathic Arthritis Versus Non-Juvenile Idiopathic Arthritis Patients with Arthralgia

This retrospective case–control study aimed to evaluate whether Magnetic Resonance Imaging (MRI) enables differentiation of ankle arthritis in Juvenile Idiopathic Afrthritis JIA from ankle arthralgia of unknown aetiology in patients clinically suspected of JIA. Forty-four children, at ages 5–16, who underwent MRI of the ankle from January 2016 to March 2021 for clinically suspected active ankle arthritis in the course of JIA were included. MRI findings in both groups—patients with the final diagnosis of JIA and without final diagnosis of JIA—were compared and scored. The sum of the scores of 22 ankle lesions in an individual patient (active, destructive and developmental), so-called the MRI summarized score, was calculated and tested in terms of the most optimal diagnosis of JIA. Interobserver agreement was calculated. Inflammatory features were seen on MRI in 38 out of all the included patients (86%). The most common lesions in both groups were effusion in the tibio-talar joint (68% in JIA and 64% in the arthralgia group) and effusion in subtalar joint (64% in JIA vs. 59% in the arthralgia group). In general, more lesions were identified in the JIA group than in non-JIA. However, only tenosynovitis was significantly more common in the JIA vs. non-JIA group (p = 0.031). The MRI summarized score did not allow for discrimination between ankle arthritis in JIA from non-JIA patients; the best levels of sensitivity (32%), specificity (91%), positive predictive value PPV (78%) and negative predictive value NPV (57%) were achieved only at the cut-off point of 10.

Juvenile Dermatomyositis Magnetic Resonance Imaging Score (JIS) does not correlate with criteria for clinically inactive disease: a single-centre retrospective evaluation

The Paediatric Rheumatology International Trials Organisation (PRINTO) criteria for clinically inactive disease (CID) and their proposal for glucocorticoid tapering do not consider MRI findings, despite the growing use of MRI and development of reliable MRI scoring tools. We aim to evaluate how CID correlates with MRI scores and physician decision making. We retrospectively used the Juvenile Dermatomyositis Imaging Score (JIS) to score MRIs of all children with JDM over a 10-year period. Demographic, diagnosis, treatment and core set measures data were collected. Correlation between CID and JIS was assessed as well as correlation with the physician treatment decision. There were 25 patients with 59 follow-up episodes to analyse correlation between physician treatment decision and JIS; and 50 episodes for the CID category and JIS correlation. JIS was not significantly associated with the CID category but did correlate with the physician decision. No significant association was found between clinical decision and CID category. The JIS area under the ROC curve (AUC) was 0.80 (95% CI 0.62-0.99) with a score ≥ 8 to predict an escalation. JIS sensitivity and specificity were both 78% with accuracy of 78%, compared to only 67%, 46% and 49%, respectively, for the CID criteria. Clinical criteria alone are not sufficient to assess disease activity status. Clinical decision trends correlated to MRI findings but not PRINTO CID criteria. Multi centre prospective studies are needed to replicate our findings and establish how to best use MRI as a biomarker of disease activity.

MRI Findings in Hip in Juvenile Idiopathic Arthritis

The aim of this study was to evaluate if magnetic resonance imaging allows hip arthritis in JIA to be differentiated from hip arthralgia of unknown etiology in juveniles clinically suspected for hip arthritis. This was a retrospective observational study which included 97 children with clinically suspected hip arthritis. Each hip was assessed and scored in MRI for signs of active and destructive inflammatory lesions and developmental lesions. MRI findings between JIA-confirmed patients and without final diagnosis of JIA were compared and the MRI summarized score was calculated, as the sum of scorings of all 24 hip lesions in an individual patient (i.a., effusion, synovitis, bone marrow edema, enthesitis). MRI showed at least one lesion in the majority of patients (95 patients; 98%). Effusion was the most common feature, followed by bone marrow oedema and synovitis. All lesions were more common in patients with a final diagnosis of JIA, especially synovitis and enthesitis (p = 0.037 and p = 0.047). The MRI summarized score was significantly higher in the JIA group than the non-JIA group: 3 (2–5) vs. 2 (2–2), respectively, p = 0.002. Using a cut-off score of 6, the MRI summarized score showed 25% sensitivity and 100% specificity indicating a good ability in discriminating hip arthritis during JIA from non-JIA patients. MRI allows hip arthritis in JIA to be differentiated from hip arthralgia of unknown etiology with good specificity, thus, may be helpful in confirming the diagnosis of JIA.

Pervasive inflammatory activation in patients with deficiency in very-long-chain acyl-coA dehydrogenase (VLCADD)

OBJECTIVES

Very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD) is a disorder of fatty acid oxidation. Symptoms are managed by dietary supplementation with medium-chain fatty acids that bypass the metabolic block. However, patients remain vulnerable to hospitalisations because of rhabdomyolysis, suggesting pathologic processes other than energy deficit. Since rhabdomyolysis is a self-destructive process that can signal inflammatory/immune cascades, we tested the hypothesis that inflammation is a physiologic dimension of VLCADD.

METHODS

All subjects (n = 18) underwent informed consent/assent. Plasma cytokine and cytometry analyses were performed. A prospective case analysis was carried out on a patient with recurrent hospitalisation. Health data were extracted from patient medical records.

RESULTS

Patients showed systemic upregulation of nine inflammatory mediators during symptomatic and asymptomatic periods. There was also overall abundance of immune cells with high intracellular expression of IFNγ, IL-6, MIP-1β (CCL4) and TNFα, and the transcription factors p65-NFκB and STAT1 linked to inflammatory pathways. A case analysis of a patient exhibited already elevated plasma cytokine levels during diagnosis in early infancy, evolving into sustained high systemic levels during recurrent rhabdomyolysis-related hospitalisations. There were corresponding activated leukocytes, with higher intracellular stores of inflammatory molecules in monocytes compared to T cells. Exposure of monocytes to long-chain free fatty acids recapitulated the cytokine signature of patients.

CONCLUSION

Pervasive plasma cytokine upregulation and pre-activated immune cells indicate chronic inflammatory state in VLCADD. Thus, there is rationale for practical implementation of clinical assessment of inflammation and/or translational testing, or adoption, of anti-inflammatory intervention(s) for personalised disease management.

Connective Tissue Disorders in Childhood: Are They All the Same?

Systemic connective tissue disorders are characterized by the presence of autoantibodies and multiorgan system involvement. Juvenile systemic lupus erythematosus with or without associated antiphospholipid syndrome; juvenile dermatomyositis; sclerodermiform syndromes, including systemic and localized sclerodermas and eosinophilic fasciitis; mixed connective tissue disease; and Sjögren syndrome are the disorders that affect children most frequently. Diagnosis is difficult, because the clinical presentation of patients is diverse, from mild to severe disease. In addition, all organs may be affected. However, a variety of imaging techniques are now available to investigate rheumatic disease in children. These imaging modalities offer the potential for earlier diagnosis and improved assessment of therapeutic response. This article reviews the main connective tissue disorders that affect children, highlighting their key imaging features on images acquired with different diagnostic imaging modalities and correlating these features with clinical and pathologic findings, when available. ^©RSNA, 2019.

Inter- and intra-observer reliability of contrast-enhanced magnetic resonance imaging parameters in children with suspected juvenile idiopathic arthritis of the hip

BACKGROUND

Previous work at our institution demonstrated discrepancies between radiologists in interpretation of contrast-enhanced magnetic resonance imaging (MRI) in suspected hip arthritis.

OBJECTIVE

To assess inter- and intra-observer reliability of selected MRI parameters (effusion, marrow oedema and synovial thickness and enhancement) used in the diagnosis of juvenile idiopathic arthritis.

MATERIALS AND METHODS

A retrospective cohort study was conducted of patients with confirmed or suspected juvenile idiopathic arthritis who underwent hip contrast-enhanced MRI between January 2011 and September 2014. Three pediatric musculoskeletal radiologists independently assessed all scans for effusion, marrow oedema, measurement of synovial thickness, synovial enhancement and subjective assessment of synovium. Categorical variables were analysed using the Cohen κ, and measurement using Bland-Altman plots.

RESULTS

Eighty patients were included. Interobserver reliability was moderate for effusion (κ=0.5-0.7), marrow oedema (κ=0.6), subjective synovial assessment (κ=0.4-0.5) and synovial enhancement (κ=0.1-0.5). Intra-observer reliability was highest for marrow oedema (κ=0.6-0.8) and lowest for effusion (κ=0.4-0.7). Intra-observer reliability for synovial enhancement (κ= -0.7-0.8) and subjective synovial assessment (κ=0.4-1.0) ranged from poor to excellent. For synovial thickness, intra- and interobserver Bland-Altman plots were well clustered around the mean suggesting good agreement.

CONCLUSION

There were large differences across variables and only moderate agreement between observers. The most reliable parameters were presence of joint effusion and bone marrow oedema and subjective assessment of synovium.

In vivo measurement of membrane permeability and myofiber size in human muscle using time-dependent diffusion tensor imaging and the random permeable barrier model

The time dependence of the diffusion coefficient is a hallmark of tissue complexity at the micrometer level. Here we demonstrate how biophysical modeling, combined with a specifically tailored diffusion MRI acquisition performing diffusion tensor imaging (DTI) for varying diffusion times, can be used to determine fiber size and membrane permeability of muscle fibers in vivo. We describe the random permeable barrier model (RPBM) and its assumptions, as well as the details of stimulated echo DTI acquisition, signal processing steps, and potential pitfalls. We illustrate the RPBM method on a few pilot examples involving human subjects (previously published as well as new), such as revealing myofiber size derived from RPBM increase after training in a calf muscle, and size decrease with atrophy in shoulder rotator cuff muscle. Finally, we comment on the potential clinical relevance of our results. Copyright © 2016 John Wiley & Sons, Ltd.

Muscle MRI in patients with long-chain fatty acid oxidation disorders

INTRODUCTION

Muscle magnetic resonance imaging (MRI) is a useful tool for visualizing abnormalities in neuromuscular disorders. The value of muscle MRI has not been studied in long-chain fatty acid oxidation (lcFAO) disorders. LcFAO disorders may present with metabolic myopathy including episodic rhabdomyolysis.

OBJECTIVE

To investigate whether lcFAO disorders are associated with muscle MRI abnormalities.

METHODS

Lower body MRI was performed in 20 patients with lcFAO disorders, i.e. three carnitine palmitoyltransferase 2 deficiency (CPT2D), 12 very long-chain acyl-CoA dehydrogenase deficiency (VLCADD), three mitochondrial trifunctional protein deficiency (MTPD) and two isolated long-chain hydroxyacyl-CoA dehydrogenase deficiency (LCHADD).

RESULTS

At the time of MRI, four patients had muscle weakness, 14 had muscle pain and 13 were exercise intolerant. Median creatine kinase (CK) level of patients at the day of MRI was 398 U/L (range 35-12,483). T1W and STIR signal intensity (SI) were markedly increased in MTPD patients from girdle to lower leg. VLCADD patients showed predominantly proximal T1W SI changes, whereas LCHADD patients mostly showed distal T1W SI changes. Prominent STIR weighted signal intensity increases of almost all muscle groups were observed in patients with VLCADD and LCHADD with very high CK (>11.000) levels.

CONCLUSIONS AND RELEVANCE

lcFAO disorders are associated with specific patterns of increased T1W and STIR signal intensity. These patterns may reflect lipid accumulation and inflammation secondary to lcFAO defects and progressive muscle damage. Future studies are needed to investigate whether muscle MRI might be a useful tool to monitor disease course and to study pathogenesis of lcFAO related myopathy.

MRI guided wire localization muscle biopsy in a child with juvenile dermatomyositis

A novel technique for preoperative MRI guided wire localization for targeted surgical excisional biopsy of muscle is described in a pediatric patient with juvenile dermatomyositis (JDM). This technique allows for preoperative localization of abnormalities seen only with MRI. Using this technique, the patient underwent successful targeted muscle biopsy for confirmation of the diagnosis and staging of dermatomyositis.

Clinical analysis in 202 children with juvenile idiopathic arthritis

This study attempts to characterize the clinical features of various subtypes of juvenile idiopathic arthritis (JIA) and try to investigate the prognostic factors. Patients with JIA hospitalized in Nanjing Children Hospital during April 2005 to April 2010 were enrolled. Clinical manifestations and laboratory parameters were retrospectively reviewed. A total of 202 cases were included, 105 males and 97 females, with average age at onset of 7.5 years. Patients with systemic JIA were most common, accounting for 47.0%. Fever, rash, and arthritis were the most common clinical manifestations. The most commonly involved joints were the knee and ankle. Laboratory parameters were significantly different but not specific. Time from onset to treatment, hepatomegaly, and involvement of wrist may have a significant effect on the outcome. A total of 117 cases were followed up, with an average follow-up time of 2 years. Among them, 55 cases achieved complete remission, 27 cases with partial remission, and 29 cases without remission, and six died. JIA is a heterogeneous disease with varied onset and clinical manifestations, which makes treatment a serious challenge. Receiving treatment late, hepatomegaly, and impaired wrist were early risk factors for an unfavorable outcome.

The diagnostic accuracy of unenhanced MRI in the assessment of joint abnormalities in juvenile idiopathic arthritis

OBJECTIVES

To assess the diagnostic accuracy and reliability of MRI without contrast enhancement in the evaluation of JIA knee joint abnormalities.

METHODS

JIA patients with clinically active knee involvement were prospectively studied using an 1-T open-bore magnet. MRI features were independently evaluated by two readers using the JAMRIS system. The first reading included unenhanced images, whereas complete image sets were available for the second reading.

RESULTS

Imaging findings from 73 patients were analysed. Agreement between Gd-enhanced (+Gd) and Gd-unenhanced (-Gd) MRI scores of bone marrow changes, cartilage lesions and bone erosions was good concerning sensitivity, specificity, negative predictive value and positive predictive value. Inter-observer agreement was good for both -Gd and +Gd scores (ICC = 0.91-1.00, 0.93-1.00, respectively). Regarding the assessment of synovial hypertrophy, specificity of -Gd was high (0.97), but the sensitivity of unenhanced MRI was only 0.62. Inter-reader agreement for +Gd MRI was ICC = 0.94; however, omitting post-Gd acquisitions increased inter-reader variation (ICC = 0.86).

CONCLUSIONS

If Gd-enhanced MRI is the reference standard, omitting Gd contrast medium is irrelevant for the assessment of bone marrow changes, cartilage lesions and bone erosions as joint abnormalities in JIA. Omitting intravenous Gd in the MRI assessment of joints in JIA is inadvisable, because it decreases the reliability of detecting synovial disease.

KEY POINTS

• Magnetic resonance imaging is increasingly used to assess juvenile idiopathic arthritis. • Synovial hypertrophy, a marker of JIA activity, is well shown by MRI. • Omitting intravenous contrast medium decreases the reliability of synovial hypertrophy scores. • Bone marrow, cartilage and erosions can be reliably evaluated without contrast enhancement. • In the evaluation of JIA disease activity, unenhanced MRI is inadvisable.

Juvenile dermatomyositis

Juvenile dermatomyositis (JDM) is a systemic, inflammatory, idiopathic disease, mainly affecting the skin and the muscles, starting before the age of 16, with an incidence around one case per 1 million children. Some patients display typical features of JDM without skin involvement, or even without muscle involvement; however, both tissues are affected over time in most cases. Diagnosis criteria were established by Bohan and Peter 35 years ago, based on the presence of typical skin rash and proximal muscle involvement. Other conditions have to be ruled out before making a diagnosis of JDM, such as other connective tissue diseases, polymyositis, infectious/postinfectious myositis, genetic diseases, or metabolic or drug-induced myopathies. Unlike adult-onset dermatomyositis, JDM is exceptionally associated with a malignant disease. JDM may also affect several organs, including the lungs and the digestive tract. In a subset of patients, glucose intolerance, lipodystrophia and/or calcinosis develop. Delay in treatment initiation or inadequate treatment may favor diffuse, debilitating calcinosis. JDM patients have to be referred to reference pediatric centers to properly assess disease activity and disease-related damage (including low bone density in most cases), and to define the best treatment. Long-lasting corticosteroid therapy remains the gold standard, together with physiotherapy. Ongoing clinical trials are assessing the effect of several immunosuppressive and immunomodulatory drugs, which may help to control the disease and possibly demonstrate a corticosteroid-sparing effect. Most patients respond to treatment; relapses are frequent but a complete disease remission is achieved in most cases before adulthood.

Idiopathic inflammatory myopathies in childhood: current concepts

The juvenile idiopathic inflammatory myopathies are a group of rare, chronic, multisystem, autoimmune diseases associated with muscle weakness. This article reviews practical issues of relevance to pediatricians, including clinical presentation, differential diagnosis, investigation, therapy, and prognosis. The importance of early recognition and specialist involvement is emphasized.

Actuality of juvenile dermatomyositis

Juvenile dermatomyositis is a rare disorder, but remains the most commonly occurring chronic inflammatory myopathy among children. Other than the proximal muscles and skin, which are routinely affected, vasculopathy may affect other viscera and can be multisystemic. A redefinition of the diagnostic criteria is currently underway and is likely to lead to other clinical signs and to sensitive and non-invasive examinations such as MRI. The impact of juvenile dermatomyositis on health and quality of life remains significant despite systemic corticosteroid therapy and immunosuppressor treatment, which have considerably improved the prognosis. Numerous predictors for favourable and pejorative evolution have been identified. The standardisation and the generalisation of clinical assessment tools will make it possible to carry out the clinical trials required to determine the relevance of the new therapeutic options available for children.

Long-term muscular outcome and predisposing and prognostic factors in juvenile dermatomyositis: A case-control study

OBJECTIVE

To compare muscle strength, physical health, and HLA-DRB1 allele carriage frequencies in patients with longstanding juvenile dermatomyositis (DM) with that of controls, and to determine the presence of and risk factors for muscle weakness and magnetic resonance imaging (MRI)-detected muscle damage in juvenile DM patients.

METHODS

Fifty-nine patients with juvenile DM examined a median of 16.8 years (range 2.0-38.1 years) after disease onset were compared with 59 age- and sex-matched controls. Muscle strength/endurance was measured by manual muscle testing (MMT) and the Childhood Myositis Assessment Scale (CMAS); health status was measured by the Short Form 36. HLA-DRB1 alleles were determined by sequencing in patients and 898 healthy controls. In patients, disease activity/damage was measured by the Disease Activity Score (DAS), Myositis Damage Index (MDI), Health Assessment Questionnaire/Childhood Health Assessment Questionnaire, and MRI scans of the thigh muscles. Early disease characteristics were obtained by chart review.

RESULTS

Patients had lower muscle strength/endurance (P < 0.001 for both) and physical health (P = 0.014) and increased HLA-DRB1*0301 (P = 0.01) and DRB1*1401 (P = 0.003) compared with controls. In patients, persistent muscle weakness was found in 42% with MMT (score <78) and in 31% with the CMAS (score <48), whereas MRI-detected muscle damage was found in 52%. Muscle weakness and MRI-detected muscle damage were predicted by MDI muscle damage and a high DAS 1 year postdiagnosis.

CONCLUSION

A median of 16.8 years after disease onset, juvenile DM patients were weaker than the controls; muscle weakness/reduced endurance was found in 31-42% of patients and MRI-detected muscular damage was found in 52% of patients. The outcomes were predicted by high disease activity and muscle damage present 1 year postdiagnosis.

Update on the assessment of children with juvenile idiopathic inflammatory myopathy

The availability of validated measurement tools to assess children with juvenile idiopathic inflammatory myopathies is critical to clinical care and to ongoing research into new therapeutic modalities and approaches. Recent work has led to the development of tools for assessment of muscle strength and physical function, skin disease, global disease activity and damage, extramuscular disease, and quality of life. Ongoing work is attempting to integrate these assessments into core sets and definitions of improvement and flare. Future work will refine these assessments and definitions and--where there are multiple choices--determine which tools constitute an optimal assessment.