Heterotopic ossifications of the TMJ may be seen in children with JIA and are associated with particularly severe TMJ arthritis, joint destruction, and pannus formation. Pathology from these joints suggests that the heterotopic ossification may result from multiple pathological processes.

Cytomegalovirus (CMV) is a ubiquitous virus that usually results in asymptomatic or clinically benign infection. However, there are two groups of patients whose response to CMV infection is much more severe: those who are infected during fetal development and those who are immunocompromised. Although the manifestations of these types of infection differ, both often result in substantial neurologic sequelae. Imaging plays a key role in the diagnosis of both congenital and acquired CMV infection. Neurologic findings of congenital CMV infection include intracranial calcification, migrational abnormalities, cerebral and cerebellar volume loss, ventriculomegaly, and white matter disease. The presence of these findings in children with neurodevelopmental delays is suggestive of congenital CMV infection, even if the child was asymptomatic at birth. Certain imaging features also may indicate future neurologic deficits in symptomatic infants. Acquired CMV infection is potentially deadly in immunocompromised patients such as those infected with human immunodeficiency virus or with acquired immune deficiency syndrome and those with a history of solid organ or bone marrow transplantation. Imaging findings of acquired CMV infection often are nonspecific; however, they may indicate a need for further serologic analysis to determine if CMV infection is present. Early recognition and treatment of central nervous system CMV infection is vital for effective treatment, and familiarity with the imaging findings of this common infection is important for accurate diagnosis.

These findings identify new US criteria that compare favorably to CT. In children with suspected appendicitis, using US as the initial imaging study will ultimately lead to improved accuracy, lower cost and the elimination of ionizing radiation exposure.

Radiographic evaluation of elbow trauma in the acute setting requires a firm understanding of developmental anatomy, radiographic landmarks, and the common injury patterns. Both radiography and MRI are vital tools for diagnosing chronic elbow overuse injuries in adolescent athletes.

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OBJECTIVE The introduction of MDCT has increased the utilization of CT in pediatric radiology along with concerns for radiation sequelae. This article reviews general principles of lowering radiation dose, the basic physics that impact radiation dose, and specific CT integrated dose-reduction tools focused on the pediatric population. CONCLUSION The goal of this article is to provide a comprehensive review of the recent literature regarding CT dose reduction methods, their limitations, and an outlook on future developments with a focus on the pediatric population. The discussion will initially focus on general considerations that lead to radiation dose reduction, followed by specific technical features that influence the radiation dose.

Objective.Serial magnetic resonance imaging (MRI) examinations are often needed in chronic nonbacterial osteomyelitis (CNO) to determine the objective response to treatment. Our objectives in this study were (1) to develop a consensus-based MRI scoring tool for clinical and research use in CNO; and (2) to evaluate interrater reliability and agreement using whole-body (WB)-MRI from children with CNO.Methods.Eleven pediatric radiologists discussed definitions and grading of signal intensity, size of signal abnormality within bone marrow, and associated features on MRI through monthly conference calls and a consensus meeting, using a nominal group technique in July 2017. WB-MRI scans from children with CNO were deidentified for training reading and an interrater reliability study. The reading by each radiologist was conducted in a randomized order. Interrater reliability for abnormal signal and severity were assessed using free-marginal κ statistics.Results.Radiologists reached a consensus on grading CNO-specific MRI findings and on describing bone units based on anatomy. A total of 45 sets of WB-MRI scans, including 4 sets of non-CNO MRI examinations, were selected for the final reading. The mean κ of each category of bones was > 0.7 with majority > 0.9 demonstrating substantial/almost perfect interrater reliability of readings among radiologists. The agreement on signal intensity and the size of signal abnormality within the most commonly affected bones (femur and tibia) were lower than those of other bones.Conclusion.The chronic nonbacterial osteomyelitis magnetic resonance imaging scoring (CROMRIS) tool is a comprehensive standardized scoring tool for MRI in children with CNO. Our interrater study demonstrated good interrater reliability and agreement of readings.

Juvenile idiopathic arthritis (JIA) and osteoarticular infection can cause nonspecific articular and periarticular complaints in children. Although contrast material-enhanced magnetic resonance imaging is the reference standard imaging modality, musculoskeletal ultrasonography (US) is emerging as an important adjunct imaging modality that can provide valuable information relatively quickly without use of radiation or the need for sedation. However, diagnostic accuracy requires a systemic approach, familiarity with various US techniques, and an understanding of maturation-related changes. Specifically, the use of dynamic, Doppler, and/or multifocal US assessments can help confirm sites of disease, monitor therapy response, and guide interventions. In patients with JIA, ongoing synovial inflammation can lead to articular and periarticular changes, including synovitis, tenosynovitis, cartilage damage, bone changes, and enthesopathy. Although these findings can manifest in adult patients with rheumatoid arthritis, important differences and pitfalls exist because of the unique changes associated with an immature and maturing skeleton. In patients who are clinically suspected of having osteoarticular infection, the inability of US to evaluate the bone marrow decreases its sensitivity. Therefore, the US findings should be interpreted with caution because juxtacortical inflammation is suggestive, but neither sensitive nor specific, for underlying osteomyelitis. Similarly, the absence of a joint effusion makes septic arthritis extremely unlikely but not impossible. US findings of JIA and osteoarticular infection often overlap. Although certain clinical scenarios, laboratory findings, and imaging appearances can favor one diagnosis over the other, fluid analysis may still be required for definitive diagnosis and optimal treatment. US is the preferred modality for fluid aspiration and administering intra-articular corticosteroid therapy. RSNA, 2017.