A novel radiographic scoring system for growth abnormalities and structural change in children with juvenile idiopathic arthritis of the hip

Background: Approximately 20\u201350% of children with juvenile idiopathic arthritis (JIA) have hip involvement within 6 years of diagnosis. Scoring systems for hip-related radiographic changes are lacking. Objective: To examine precision of potential radiographic variables and to suggest a scoring system. Materials and methods: We reviewed a set of 75 pelvic radiographs from 75 children with JIA hip involvement across two European centres. We assessed findings of (1) destructive change and (2) growth abnormality, according to a pre-defined scoring system. All radiographs were scored independently by two sets of radiologists. One set scored the radiographs a second time. We used kappa statistics to rate inter- and intra-observer variability. Results: Assessment of erosions of the femoral head, femoral neck and the acetabulum showed moderate to good agreement for the same reader (kappa of 0.5\u20130.8). The inter-reader agreement was, however, low (kappa of 0.1\u20130.3). There was moderate to high agreement for the assessment of femoral head flattening (kappa of 0.6\u20130.7 for the same reader, 0.3\u20130.7 between readers). Joint space narrowing showed moderate to high agreement both within and between observers (kappa of 0.4\u20130.8). Femoral neck length and width measurements, the centrum\u2013collum\u2013diaphysis angle, and trochanteric\u2013femoral head lengths were relatively precise, with 95% limits of agreement within 10\u201315% of the observer average. Conclusion: Several radiographic variables of destructive and growth abnormalities in children with hip JIA have reasonable reproducibility. We suggest that future studies on clinical validity focus on assessing only reproducible radiographic variables

Whole-body MRI in children and adolescents: Can T2-weighted Dixon fat-only images replace standard T1-weighted images in the assessment of bone marrow?

Objective: When performing whole-body MRI for bone marrow assessment in children, optimizing scan time is crucial. The aim was to compare T2 Dixon fat-only and TSE T1-weighted sequences in the assessment of bone marrow high signal areas seen on T2 Dixon water-only in healthy children and adolescents. Materials and methods: Whole-body MRIs from 196 healthy children and adolescents aged 6 to 19 years (mean 12.0) were obtained including T2 TSE Dixon and T1 TSE-weighted images. Areas with increased signal on T2 Dixon water-only images were scored using a novel, validated scoring system and classified into “minor” or “major” findings according to size and intensity, where “major” referred to changes easily being misdiagnosed as pathology in a clinical setting. Areas were assessed for low signal on T2 Dixon fat-only images and, after at least three weeks to avoid recall bias, on the T1-weighted sequence by two experienced pediatric radiologists. Results: 1250 high signal areas were evaluated on T2 Dixon water-only images. In 1159/1250 (92.7%) low signal was seen on both T2 Dixon fat-only and T1-weighted sequences while in 24 (1.9%) it was not present on either sequence, with an absolute agreement of 94.6%. Discordant findings were found in 67 areas, of which in 18 (1.5%) low signal was visible on T1-weighted images alone and in 49 (3.9%) on T2 Dixon fat-only alone. The overall kappa value between the two sequences was 0.39. The agreement was higher for major as compared to minor findings (kappa values of 0.69 and 0.29, respectively) and higher for the older age groups. Conclusion: T2 Dixon fat-only can replace T1-weighted sequence on whole-body MRI for bone marrow assessment in children over the age of nine, thus reducing scan time

Whole body magnetic resonance imaging in healthy children and adolescents: Bone marrow appearances of the appendicular skeleton

Objective: To describe the appearances of bone marrow in the appendicular skeleton on fat-suppressed T2- weighted sequences as assessed by whole-body MRI in healthy and asymptomatic children and adolescents. Material and methods: Following ethical approval, we assessed the bone marrow of the extremities on water-only Dixon T2-weighted images as part of a whole-body MRI in 196 healthy and asymptomatic children aged 5–19 years. Based on a newly devised and validated scoring system, we graded intensity (0–2 scale) and extension (1–4 scale) of focal high signal bone marrow areas, and divided them into minor or major findings, based on intensity and extension, reflecting their potential conspicuousness in a clinical setting. Results: In the upper extremity, we registered 366 areas with increased signal whereof 79 were major findings. In the lower extremities there were 675 areas of increased signal of which 340 were major findings. Hundred-andfifteen (58.79%) individuals had at least one major finding, mainly located in the hand and proximal humerus, and the feet and knees. We found no differences according to gender, reported hours of sports activity, handedness, or age group, except for more minor findings in the upper extremities amongst 15–18-year-olds as compared to those aged 5–8 years. Conclusion: Focal areas of high signal intensity on whole-body MRI, T2-weighted fat suppressed images that, in a clinical setting could cause concern, were seen in more than half of healthy, asymptomatic children and adolescents. Awareness of this is important when interpreting whole-body MRI in this age group, particularly in the assessment of clinically silent lesions

An image-based kinematic model of the tibiotalar and subtalar joints and its application to gait analysis in children with Juvenile Idiopathic Arthritis

In vivo estimates of tibiotalar and the subtalar joint kinematics can unveil unique information about gait biomechanics, especially in the presence of musculoskeletal disorders affecting the foot and ankle complex. Previous literature investigated the ankle kinematics on ex vivo data sets, but little has been reported for natural walking, and even less for pathological and juvenile populations. This paper proposes an MRI-based morphological fitting methodology for the personalised definition of the tibiotalar and the subtalar joint axes during gait, and investigated its application to characterise the ankle kinematics in twenty patients affected by Juvenile Idiopathic Arthritis (JIA). The estimated joint axes were in line with in vivo and ex vivo literature data and joint kinematics variation subsequent to inter-operator variability was in the order of 1°. The model allowed to investigate, for the first time in patients with JIA, the functional response to joint impairment. The joint kinematics highlighted changes over time that were consistent with changes in the patient’s clinical pattern and notably varied from patient to patient. The heterogeneous and patient-specific nature of the effects of JIA was confirmed by the absence of a correlation between a semi-quantitative MRI-based impairment score and a variety of investigated joint kinematics indexes. In conclusion, this study showed the feasibility of using MRI and morphological fitting to identify the tibiotalar and subtalar joint axes in a non-invasive patient-specific manner. The proposed methodology represents an innovative and reliable approach to the analysis of the ankle joint kinematics in pathological juvenile populations

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

A Patient-Specific Foot Model for the Estimate of Ankle Joint Forces in Patients with Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is the leading cause of childhood disability from a musculoskeletal disorder. It generally affects large joints such as the knee and the ankle, often causing structural damage. Different factors contribute to the damage onset, including altered joint loading and other mechanical factors, associated with pain and inflammation. The prediction of patients' joint loading can hence be a valuable tool in understanding the disease mechanisms involved in structural damage progression. A number of lower-limb musculoskeletal models have been proposed to analyse the hip and knee joints, but juvenile models of the foot are still lacking. This paper presents a modelling pipeline that allows the creation of juvenile patient-specific models starting from lower limb kinematics and foot and ankle MRI data. This pipeline has been applied to data from three children with JIA and the importance of patient-specific parameters and modelling assumptions has been tested in a sensitivity analysis focused on the variation of the joint reaction forces. This analysis highlighted the criticality of patient-specific definition of the ankle joint axes and location of the Achilles tendon insertions. Patient-specific detection of the Tibialis Anterior, Tibialis Posterior, and Peroneus Longus origins and insertions were also shown to be important

Pediatric whole-body magnetic resonance imaging: comparison of STIR and T2 Dixon sequences in the detection and grading of high signal bone marrow changes

Objectives To compare short time inversion recovery (STIR) and T2 Dixon in the detection and grading of high signal intensity areas in bone marrow on whole-body MRI in healthy children. Methods Prospective study, including whole-body 1.5-T MRIs from 77 healthy children. Two experienced radiologists in consensus identifed and graded areas of high bone marrow signal on STIR and T2-weighted (T2W) turbo spin echo (TSE) Dixon images (presence, extension) in two diferent sessions at an interval of at least 3 weeks. In a third session, a third observer joined the two readers for an additional consensus reading with all sequences available (substitute gold standard). Results Four hundred ninety of 545 (89.9%) high signal areas were visible on both sequences, while 27 (5.0%) were visible on STIR only and 28 (5.1%) on T2W Dixon only. Twenty-four of 27 (89%) lesions seen on STIR only, and 25/28 (89%) seen on T2W Dixon only, were graded as mildly increased signal intensity. The proportion of true positive high signal lesions was higher for the T2W Dixon images as compared to STIR (74.2% vs. 68.2%) (p=0.029), while the proportion of false negatives was lower (25.9% vs. 31.7% (p=0.035) for T2W Dixon and STIR, respectively). There was a moderate agreement between the T2W Dixon and STIR-based extension scores on a 0–4 scale, with a kappa of 0.45 (95% CI=0.34–0.56). Conclusions Most high signal bone marrow changes identifed on a 1.5-T whole-body MRI were seen on both STIR and water-only T2W Dixon, underscoring the importance of using identical protocols when following bone-marrow signal changes over time

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

Carpal erosions in children with juvenile idiopathic arthritis: repeatability of a newly devised MR-scoring system

Background: Juvenile idiopathic arthritis (JIA) is characterized by synovial inflammation, with potential risk of developing progressive joint destruction. Personalized state-of-the-art treatment depends on valid markers for disease activity to monitor response; however, no such markers exist. Objective: To evaluate the reliability of scoring of carpal bone erosions on MR in children with JIA using two semi-quantitative scoring systems. Materials and methods: A total of 1,236 carpal bones (91 MR wrist examinations) were scored twice by two independent pediatric musculoskeletal radiologists. Bony erosions were scored according to estimated bone volume loss using a 0\u20134 scale and a 0\u201310 scale. An aggregate erosion score comprising the sum total carpal bone volume loss was calculated for each examination. Results: The 0\u20134 scoring system resulted in good intra-reader agreement and moderate to good inter-observer agreement in the assessment of individual bones. Fair and moderate agreement were achieved for inter-reader and intra-reader agreement, respectively, using the 0\u201310 scale. Intra- and particularly inter-reader aggregate score variability were much less favorable, with wide limits of agreement. Conclusion: Further analysis of erosive disease patterns compared with normal subjects is required, and to facilitate the development of an alternative means of quantifying disease