Imaging in juvenile idiopathic arthritis (JIA): an update with particular emphasis on MRI.

Juvenile idiopathic arthritis (JIA) is a heterogeneous condition encompassing all forms of chronic arthritis of unknown origin and with onset before 16 years of age. During the last decade new, potent therapeutic agents have become available, underscoring the need for accurate monitoring of therapeutic response on both disease activity and structural damage to the joint. However, so far, treatment efficacy is based on clinical ground only, although clinical parameters are poor markers for disease activity and progression of structural damage. Not so for rheumatoid arthritis patients where the inclusion of radiographic assessment has been required by FDA to test the disease-modifying potential of new anti-rheumatic drugs. In imaging of children with JIA there has been a shift from traditional radiography towards newer techniques such as ultrasound and MRI, however without proper evaluation of their accuracy and validity. We here summarize present knowledge and discuss future challenges in imaging children with JIA.

Primary aneurysmal bone cysts in children: percutaneous sclerotherapy with absolute alcohol and proposal of a vascular classification.

BACKGROUND: Percutaneous sclerotherapy is an effective treatment for aneurysmal bone cysts (ABCs). OBJECTIVE: The purpose of this study was to demonstrate the safety and efficacy of sclerotherapy with absolute alcohol and to propose a vascular classification of ABCs based on a retrospective review. MATERIALS AND METHODS: This was a review of children treated with absolute alcohol sclerotherapy for ABC at a single institution from January 1995 until November 2009. Treatment response was evaluated radiographically and clinically. Cyst fluid was classified as clear, partially bloody, or bloody. Presence of any venous drainage of the cyst was assessed by injection of contrast medium into the cyst cavity. RESULTS: Twenty-nine children with ages ranging from 2 to 16 years were included. Treatment response was good in 17 (59%), partial in 9 (31%), and poor in 3 (10%) children. Venous drainage was absent in six out of seven clear-fluid cysts, which we classified as lymphatic. Drainage was present in all seven bloody-fluid cysts, which we classified as venous. In seven partially bloody-fluid cysts, venous drainage was seen in three. CONCLUSION: Sclerotherapy with absolute alcohol is a safe and effective treatment of ABC. We propose classifying ABC as lymphatic or venous and suggest considering ABC intraosseous slow-flow vascular malformations.

The paediatric wrist revisited: redefining MR findings in healthy children.

OBJECTIVES: During a multicentre study on juvenile idiopathic arthritis, wide variations were observed in bone shape, signal intensity and volume of joint fluid as shown by MRI which in part appeared to be unrelated to disease activity. A study was undertaken to examine these features in a cohort of healthy children. METHODS: 88 children of mean age 9.8 years (range 5-15) underwent MRI imaging (T1-weighted Spin Echo and Spectral Selection Attenuated Inversion Recovery (SPAIR)) of the left wrist. The number of bony depressions, distribution and amount of joint fluid and the presence of bone marrow changes were assessed. RESULTS: Bony depressions were present in all children, increasing with age from a mean of 4.0 in children aged 4-6 years to 9.2 in those aged 12-15 years (p<0.001)). 45 of 84 children (53.6%) had a high signal on SPAIR with a corresponding low signal on T1 in at least one bone. No associations were seen between bone marrow change (present or not) and sex (p=0.827) or sports club membership (p=0.616). All children had visible joint fluid in at least one of the joints assessed. No associations were seen between the presence of joint fluid and age group, except for the radius/scaphoid and capitate-scaphoid joints and a recess lateral to the hamate. CONCLUSIONS: It is important to be aware of the high prevalence of bony depressions, signal changes suggestive of bone marrow oedema and the volume of joint fluid seen in normal children. Such findings must be interpreted with care in children with suspected disease such as juvenile arthritis.

[Pigmented villonodular synovitis in children: review of six cases]. / La synovite villonodulaire de l'enfant : une revue de six cas.

PURPOSE OF THE STUDY: Pigmented villonodular synovitis is an exceptional condition in children. The clinical, biological and imaging presentation is not specific and a histology sample is required for certain diagnosis. Because of this lack of specificity, together with the rare occurrence of the disease, late diagnosis is not uncommon, making correct management an even greater challenge in the growing child. MATERIAL AND METHOD: Between 1995 and 2001, six children were treated for pigmentary villonodular synovitis, four girls and two boys, mean age 11.5 years. The knee was involved in five cases (three diffuse forms and two localized forms). One diffuse form involved the ankle. The diagnosis was suggested by the MRI findings in all patients and confirmed at the histological examination of a biopsy sample. Surgery was used in five cases and medical treatment in one patient with a diffuse form affecting the knee. A synoviorthesis (Hexatrione) was used systematically in three diffuse forms affecting the knee joint. RESULTS: Mean follow-up was 58 months. Recurrence was noted in two diffuse forms, one involving the knee at 10 months from arthroscopic synovectomy and one involving the ankle 24 months after surgical synovectomy. Systematic use of the synoviorthesis did not prevent recurrence in one case. The synoviorthesis was also used in the two cases of recurrence as a complement to surgical treatment but with no effect. Growth was not affected in any of the children. DISCUSSION: The etiopathogenic mechanism underpinning pigmented villonodular synovitis remains unclear. Genetic factors are suspected in childhood cases. MRI is the complementary examination of choice for diagnosis and follow-up. In children, treatment of pigmented villonodular synovitis depends on marginal excision of the lesion for localized forms and total synovectomy for the diffuse forms. The efficacy of the triamcinolone hexacetonide synoviorthesis remains open to debate and would require a larger series with longer follow-up for evaluation.

Characterization and prevalence of severe primary IGF1 deficiency in a large cohort of French children with short stature.

OBJECTIVE: The prevalence of severe primary IGF1 deficiency (IGFD) is unclear. IGFD must be identified promptly as treatment with recombinant human IGF1 (rhIGF1) is now available. Our objective was to characterize and assess the prevalence of severe primary IGFD in a large cohort of patients evaluated for short stature at a pediatric endocrinology unit in France. DESIGN: Observational study in a prospective cohort. METHODS: Consecutive patients referred to our unit between 2004 and 2009 for suspected slow statural growth were included. Patients were classified into eight etiological categories. IGFD was defined by height ≤-3 SDS, serum IGF1 levels <2.5th percentile, GH sufficiency, and absence of causes of secondary IGFD. RESULTS: Out of 2546 patients included, 337 (13.5%) were born small for gestational age and 424 (16.9%) had idiopathic short stature. In these two categories, we identified 30 patients who met our criterion for IGFD (30/2546, 1.2%). In these 30 patients, we assessed the response to IGF1 generation test, time course of IGF1 levels, and efficiency of GH replacement therapy. The results indicated that only four of the 30 children were definite or possible candidates for rhIGF1 replacement therapy. CONCLUSION: The prevalence of severe primary IGFD defined using the standard criterion for rhIGF1 treatment was 1.2%, and only 0.2% of patients were eligible for rhIGF1 therapy.

Unexpected high frequency of skeletal dysplasia in idiopathic short stature and small for gestational age patients.

OBJECTIVE: To assess the prevalence of skeletal dysplasias (SDs) in patients with idiopathic short stature (ISS) or small for gestational age (SGA) status. SETTING: Rare Endocrine/Growth Diseases Center in Paris, France. DESIGN: A prospective study on consecutive patients with ISS and SGA enrolled from 2004 to 2009. METHOD: We used a standardized workup to classify patients into well-established diagnostic categories. Of 713 patients with ISS (n=417) or SGA status (n=296), 50.9% underwent a skeletal survey. We chose patients labeled normal or with a prepubertal slowdown of growth as a comparison group. RESULTS: Diagnoses were ISS (16.9%), SGA (13.5%), normal growth (24.5%), transient growth rate slowing (17.3%), endocrine dysfunction (12%), genetic syndrome (8.9%), chronic disease (5.1%), and known SD (1.8%). SD was found in 20.9% of SGA and 21.8% ISS patients and in only 13.2% in our comparison group. SD prevalence was significantly higher in the ISS group than in the comparison group, especially (50%) for patients having at least one parent whose height was <-2 SDS. Dyschondrosteosis and hypochondroplasia were the most frequently identified SD, and genetic anomaly was found in 61.5 and 30% respectively. Subtle SD was found equally in the three groups and require long-term growth follow-up to evaluate the impact on final height. CONCLUSION: SD may explain more than 20% of cases of growth retardation ascribed to ISS or SGA, and this proportion is higher when parental height is <-2 SDS. A skeletal survey should be obtained in patients with delayed growth in a context of ISS or SGA.

Novel automated system for magnetic resonance imaging quantification of the inflamed synovial membrane volume in patients with juvenile idiopathic arthritis.

OBJECTIVE: To introduce a novel automated method for the quantification of the inflamed synovial membrane volume (SV) using magnetic resonance imaging (MRI), and to investigate its feasibility and validity in patients with juvenile idiopathic arthritis (JIA). METHODS: The tool was tested on 58 patients with JIA and wrist involvement. Thirty-six patients had a 1-year MRI followup. MRI of the clinically more affected wrist was performed using a 1.5T scanner and a Flex small coil. An algorithmic approach, based on supervised voxel classification for automatic estimation of SV in a 3-dimensional MRI, was developed. The SV was estimated as the number of positively classified voxels and then normalized by the patient's body surface (NSV). Validation procedures included the analysis of reliability, construct validity, responsiveness to change, discriminant validity, and the predictive value. RESULTS: The agreement between the automated estimation of NSV and the manual measurements was excellent (intraclass correlation coefficient 0.93, 95% confidence interval 0.79-0.98). The automatic NSV demonstrated good construct validity by yielding strong correlations with local signs of disease activity and a moderate correlation with global physician assessment of disease activity and with the Rheumatoid Arthritis Magnetic Resonance Imaging Scoring system synovitis score. NSV showed a strong responsiveness to clinical change (standardized response mean values >1) and satisfactory discriminant validity. High baseline NSV (>4.6) had high predictive value (100%) with respect to erosive progression. CONCLUSION: The proposed automated method allowed reliable quantification of NSV, which represents a promising imaging biomarker of disease activity in JIA. The automated system has the potential to improve the longitudinal assessment of JIA and to predict progressive joint destruction.