26-09-2017 | Pediatric | Gallery
Pediatric rheumatology
Radiologic assessment of the joints includes the analysis of periarticular soft tissue, the structure of bones forming the joint, the articular surfaces, and the joint space. Plain radiographs can give information about the increase in the periarticular soft tissue shadow (as per the x-ray on this slide), soft tissue calcifications, periarticular or diffuse osteoporosis, joint space narrowing or widening, erosions, osteolysis, bone sclerosis, periosteal reactions, osteophyte formation, and bone deformities.
Specific joint findings in juvenile idiopathic arthritis will depend on the underlying abnormality, the chronicity of the disease, and the treatment effect. The earliest abnormalities include soft tissue swelling, osteopenia, and effusion. Periosteal reaction may be seen occasionally. Typically, the osteopenia is initially periarticular, becoming more diffuse with time (as seen in this slide).
Deformity of the fingers, such as Boutonniere or swan-neck deformity, can be seen in a variety of disorders, including juvenile idiopathic arthritis (JIA) or systemic lupus erythematosus. Enlarged or irregular epiphyseal ossification centers are seen in patients with hemophilia, JIA, and tuberculous arthritis.
Enthesitis-related arthritis or juvenile spondyloarthropathies mainly involve lower limb joints in an asymmetrical fashion. Involvement of interphalangeal joint of the hallux can also be seen. New bone formation may be seen at the margins of bones. Affected joints show swelling, effusion, epiphyseal overgrowth, erosions, osteopenia, cartilage space narrowing, and rarely fusion. Swelling and periosteal new bone formation is seen in fingers and toes. Asymmetrical involvement of sacroiliac joints is seen in early disease which may later become symmetrical (as per the image on this slide). Erosions occur first on the iliac side of the sacroiliac joint. Pseudo widening occurs as a result of erosion. Sclerosis and finally ankylosis can develop.
Musculoskeletal ultrasound (US) is being increasingly used for the diagnosis and follow-up of patients with rheumatic diseases. US is helpful in the assessment of soft tissues, fluid collection, and cartilage and bone surfaces. US allows precise evaluation of synovial hyperplasia, joint effusion, cartilage damage, bone erosion, tenosynovitis, and enthesopathy.
Ultrasound (US) helps in knowing the integrity of the cartilage in the immature skeleton as it demonstrates the cartilage of unossified epiphysis and the ossific nuclei earlier than radiographs. The real-time capability of US allows dynamic assessment of joint and tendon movements, which can often aid the detection of structural abnormalities.
Power Doppler (PD) ultrasound (US) detects synovial blood flow, which is a sign of increased synovial vascularization and active inflammation (as seen in this slide). Assessment of synovial vascularization on PD is more sensitive than serum markers of inflammation in the identification of active disease. The degree of vascularity detected by PD strongly correlates with serum IL-6 levels. The sensitivity of Doppler may be further enhanced by intravascular microbubble contrast agents. Doppler enables differentiation between inactive fibrotic tissue from pannus and quantification of synovitis. US can detect tendon disease including widening of the flexor tendon sheath, loss of the normal fibrillar architecture, tears, and synovial cysts.
Magnetic resonance imaging plays an important role in musculoskeletal imaging in children. It is the preferred modality over computed tomography as it gives excellent soft tissue characterization, has no radiation, and hence is safe in children. It can also define physiological processes such as edema, loss of circulation as in avascular necrosis, and increased vascularity as in tumors. T1-weighted imaging sequence is helpful in evaluating marrow replacement, trabecular anatomy, and ligamentous abnormalities.
Proton density sequences are helpful in evaluation of fractures and ligamentous, labral, and cartilaginous anatomy.
Fluid-sensitive sequences are used for evaluation of marrow edema, ligamentous anatomy, and cartilage
Spin echo fluid-sensitive sequences are better than gradient echo sequences for the evaluation of cartilage in children. Spherical growth plate, epiphyseal cartilage, articular cartilage, and physis can be differentiated on a spin echo sequence, whereas all four types of cartilage have the same signal intensity on a gradient echo sequence.
Diffusion-weighted sequences can differentiate infective from inflammatory pathologies. Postcontrast sequences help in determining tumor vascularity, defining granulation tissue and abscess in the setting of infection, and evaluation of the synovium. In rheumatoid arthritis (RA), the early changes on magnetic resonance imaging (MRI) include synovitis, effusions, bone marrow edema, bone erosions, and tenosynovitis. RA magnetic resonance imaging score (RAMRIS) is based on these early changes and can grade the severity of disease and prognosticate outcome in adults. In children the three principal scoring systems of RAMRIS of bone marrow edema, synovitis, and bone erosions can be extrapolated to joints other than the metacarpophalangeal and wrist joint. There are no laid down systemic imaging protocols for juvenile idiopathic arthritis. The imaging protocol should be tailored to each patient. Contrast-enhanced MRI is the most sensitive imaging technique for imaging synovitis. Outcome measures in rheumatoid arthritis clinical trials (OMERACT ) defines synovitis as an area in the synovial compartment with above-normal post-gadolinium enhancement and thickness greater than the normal synovium.
Bone erosion is a sharply marginated lesion in the juxta-articular location with typical signal changes visible in two planes and cortical break in at least one plane.
Bone marrow edema is a lesion within the trabecular bone with ill-defined margins and signal characteristics of increased water content. It is considered as a very early marker of inflammation and correlates with increased levels of erythrocyte sedimentation rate and C-reactive protein.
There is no outcome measures in rheumatoid arthritis clinical trials (OMERACT) definition for tenosynovitis. Magnetic resonance imaging (MRI) reveals thickening of the synovial sheath with marked enhancement on fat-suppressed, gadolinium-enhanced, T1-weighted images. Superior ability of MRI to detect erosions may allow identification of patients with early aggressive disease with a poor prognosis.
Juvenile idiopathic arthritis can be differentiated from spondyloarthropathies as enthesitis is commonly seen in the latter. Magnetic resonance imaging (MRI) has now replaced plain X-rays for diagnosing and assessing disease activity in enthesitis-related arthritis and spondyloarthritis. It is seen mostly in the lower limbs and is usually asymmetric and is seen as an area of edema on the fluid-sensitive MRI images (see slide image). Late manifestations of enthesitis include osteopenia, bone cortex irregularity, erosions, soft tissue calcifications, and new bone formation at the bone insertion sites, but these are more commonly seen in adults.
Sacroiliitis is seen in children with enthesitis-related arthritis. Bone marrow edema, capsulitis, enthesitis, and synovitis are suggestive of active disease, and fatty infiltration/sclerosis, erosions, and bony ankylosis are suggestive of chronic disease (see slide images). Synovial enhancement has been visualized in the absence of marrow edema in children; however, in adults marrow edema is seen in all cases of synovial enhancement; hence it is advisable to give contrast in the pediatric age group, if the plain magnetic resonance imaging is normal and the clinical symptoms are present.
Magnetic resonance imaging (MRI) is highly useful in the assessment of internal derangement of the knee as they can be confused with monoarticular inflammatory arthritis. MRI has nearly 95% accuracy in the assessment of meniscal and cruciate ligament tears in the knee. MRI is the most sensitive and specific technique for the diagnosis of avascular necrosis. The MRI appearances are dependent on the stage of the disease. Idiopathic chondrolysis of the hip is an uncommon disorder, which results in extensive articular cartilage loss of the proximal femoral epiphysis and the adjoining acetabulum. The earliest changes are seen on MRI as a geometrical area of altered signal seen in medial one third of the epiphysis.
Tarsal coalitions are congenital bridging of two or more tarsal bones. Magnetic resonance imaging (MRI) and computed tomography both delineate the abnormality, whereas MRI gives additional information of the changes in the adjoining soft tissues (see image in slide).