Magnetic resonance imaging of the knee joint in juvenile idiopathic arthritis

Update on MRI in Rheumatic Diseases

Over the past decade, MRI has significantly advanced the diagnosis of rheumatic disease in both adults and juveniles. In this article, the authors present an update on MRI applications in rheumatology, based on a review of the most recent publications. New developments in adults related to, among others, axial spondyloarthritis, peripheral arthritis, and the whole body-MRI (WB-MRI) are presented. In juveniles, this update addresses the latest advancements in diagnostic MRI of peripheral joints, followed by MRI of the axial skeleton and implementation of the WB-MRI for the screening of inflammation. The authors also discuss topics of interest concerning contrast-enhanced MRI examinations in children.

Advanced Imaging of Gout and Other Inflammatory Diseases Around the Knee

The knee is one of the most commonly affected joints in the course of inflammatory arthropathies, such as crystal-induced and autoimmune inflammatory arthritis. The latter group includes systemic connective tissue diseases and spondyloarthropathies. The different pathogenesis of these entities results in their varied radiologic images. Some lead quickly to joint destruction, others only after many years, and in the remaining, destruction will not be a distinguishing radiologic feature.Radiography, ultrasonography, and magnetic resonance imaging have traditionally been the primary modalities in the diagnosis of noninflammatory and inflammatory arthropathies. In the case of crystallopathies, dual-energy computed tomography has been introduced. Hybrid techniques also offer new diagnostic opportunities. In this article, we discuss the pathologic findings and imaging correlations for crystallopathies and inflammatory diseases of the knee, with an emphasis on recent advances in their imaging diagnosis.

Surgical Treatment of Juvenile Idiopathic Arthritis in the Era of Novel Drug Therapies

Juvenile idiopathic arthritis is the most common chronic rheumatic disease encountered in children under the age of sixteen and causes significant impairments in daily life. Over the last two decades, the introduction of new drug treatments (including disease-modifying antirheumatic drugs and biologics) has changed the course of this disease, thus reducing the indication for surgery. However, some patients fail to respond to drug therapy and thus require personalized surgical management, e.g., the local reduction of joint effusion or a synovial pannus (via intra-articular corticosteroid injections, synovectomy, or soft tissue release), and management of the sequelae of arthritis (such as growth disorders and joint degeneration). Here, we provide an overview of the surgical indications and outcomes of the following interventions: intra-articular corticosteroid injections, synovectomy, soft tissue release, surgery for growth disorders, and arthroplasty.

Quantitative T2 mapping magnetic resonance imaging of articular cartilage in patients with juvenile idiopathic arthritis

PURPOSE

We aimed to analyze the microstructure changes of knee cartilage in Juvenile idiopathic arthritis (JIA) patients with active synovitis using quantitative magnetic resonance imaging (MRI) T2 mapping technique.

MATERIALS AND METHODS

This study included 23 JIA patients, who underwent bilateral knee joints by using a MR imaging protocol with the addition of a coronal T2 mapping. The femorotibial joint cartilage of participants was divided into eight subregions. Twenty-four (52.17%) of 46 joints (non-synovitis group), and twenty-two (47.83%) joint cases (active-synovitis group) were respectively calculated the T2 mean values for each subregion. Student's T test or Mann-Whitney U test was used to determine the statistical differences of each subregion in the non-synovitis and active-synovitis groups, which is also applied to define the distribution differences of cartilage subregion in femoral and tibial.

RESULTS

The T2 mean values of the superficial and deep zone of cartilage for active synovitis group were respectively higher than those for non-synovitis group (P < 0.05), except for the deep zone of cartilage in lateral tibial plateau (LTP) (P > 0.05). The mean T2 values of the deep zone in femoral cartilage for active synovitis group were significantly higher than that of tibial (P < 0.05).

CONCLUSION

The finding of an increased average T2 values in active synovitis for JIA patients, especially in the deep cartilage of femoral condyle, which suggests that T2 values may reflect cartilage microstructure differences that occur in JIA. T2 mapping as an objective and quantitative method may allow for early detection of cartilage changes.

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.

B Cells on the Stage of Inflammation in Juvenile Idiopathic Arthritis: Leading or Supporting Actors in Disease Pathogenesis?

Juvenile idiopathic arthritis (JIA) is a term that collectively refers to a group of chronic childhood arthritides, which together constitute the most common rheumatic condition in children. The International League of Associations for Rheumatology (ILAR) criteria define seven categories of JIA: oligoarticular, polyarticular rheumatoid factor (RF) negative (RF-), polyarticular RF positive (RF+), systemic, enthesitis-related arthritis, psoriatic arthritis, and undifferentiated arthritis. The ILAR classification includes persistent and extended oligoarthritis as subcategories of oligoarticular JIA, but not as distinct categories. JIA is characterized by a chronic inflammatory process affecting the synovia that begins before the age of 16 and persists at least 6 weeks. If not treated, JIA can cause significant disability and loss of quality of life. Treatment of JIA is adjusted according to the severity of the disease as combinations of non-steroidal anti-inflammatory drugs (NSAIDs), synthetic and/ or biological disease modifying anti-rheumatic drugs (DMARDs). Although the disease etiology is unknown, disturbances in innate and adaptive immune responses have been implicated in JIA development. B cells may have important roles in JIA pathogenesis through autoantibody production, antigen presentation, cytokine release and/ or T cell activation. The study of B cells has not been extensively explored in JIA, but evidence from the literature suggests that B cells might have indeed a relevant role in JIA pathophysiology. The detection of autoantibodies such as antinuclear antibodies (ANA), RF and anti-citrullinated protein antibodies (ACPA) in JIA patients supports a breakdown in B cell tolerance. Furthermore, alterations in B cell subpopulations have been documented in peripheral blood and synovial fluid from JIA patients. In fact, altered B cell homeostasis, B cell differentiation and B cell hyperactivity have been described in JIA. Of note, B cell depletion therapy with rituximab has been shown to be an effective and well-tolerated treatment in children with JIA, which further supports B cell intervention in disease development.