Osteopetrosis in the pediatric patient: what the radiologist needs to know.

Osteopetrosis describes several types of rare sclerosing bone dysplasias of varying clinical and radiographic severity. The classic autosomal dominant subtype emerges most often in adolescence but can present from infancy through adulthood. The autosomal recessive osteopetrosis, or "malignant infantile osteopetrosis," presents in infancy with a grimmer prognosis, though the autosomal dominant forms (often mislabeled as "benign") actually can have life-threatening consequences as well. Often osteopetrosis is detected due to skeletal findings on radiographs performed to evaluate injury or as an incidental finding during evaluation for illness. Given the varied phenotypic severity and presentations at different ages, radiologists play an integral role in the care of these patients both in diagnosis and in clinical evaluation and monitoring. A deeper understanding of the underlying genetic basis of the disease can aid in the radiologist in diagnosis and in anticipation of unique complications. An overview of current clinical management is also discussed.

Radiologists' Diagnostic Performance in Differentiation of Rickets and Classic Metaphyseal Lesions on Radiographs: A Multicenter Study.

BACKGROUND. Despite evidence supporting the specificity of classic metaphyseal lesions (CML) for the diagnosis of child abuse, some medicolegal practitioners claim that CML result from rickets rather than trauma. OBJECTIVE. The purpose of this study was to evaluate radiologists' diagnostic performance in differentiating rickets and CML on radiographs. METHODS. This retrospective seven-center study included children younger than 2 years who underwent knee radiography from January 2007 to December 2018 and who had either rickets (25-hydroxyvitamin D level < 20 ng/mL and abnormal knee radiographs) or knee CML and a diagnosis of child abuse from a child abuse pediatrician. Additional injuries were identified through medical record review. Radiographs were cropped and zoomed to present similar depictions of the knee. Eight radiologists independently interpreted radiographs for diagnoses of rickets or CML, rated confidence levels, and recorded associated radiographic signs. RESULTS. Seventy children (27 girls, 43 boys) had rickets; 77 children (37 girls, 40 boys) had CML. Children with CML were younger than those with rickets (mean, 3.7 vs 14.2 months, p < .001; 89.6% vs 5.7% younger than 6 months; 3.9% vs 65.7% older than 1 year). All children with CML had injuries in addition to the knee CML identified at physical examination or other imaging examinations. Radiologists had almost perfect agreement for moderate- or high-confidence interpretations of rickets (κ = 0.92) and CML (κ = 0.89). Across radiologists, estimated sensitivity, specificity, and accuracy for CML for moderate- or high-confidence interpretations were 95.1%, 97.0%, and 96.0%. Accuracy was not significantly different between pediatric and nonpediatric radiologists (p = .20) or between less experienced and more experienced radiologists (p = .57). Loss of metaphyseal zone of provisional calcification, cupping, fraying, and physeal widening were more common in rickets than CML, being detected in less than 4% of children with CML. Corner fracture, bucket-handle fracture, subphyseal lucency, deformed corner, metaphyseal irregularity, and subperiosteal new bone formation were more common in CML than rickets, being detected in less than 4% of children with rickets. CONCLUSION. Radiologists had high interobserver agreement and high diagnostic performance for differentiating rickets and CML. Recognition that CML mostly occur in children younger than 6 months and are unusual in children older than 1 year may assist interpretation. CLINICAL IMPACT. Rickets and CML have distinct radiographic signs, and radiologists can reliably differentiate these two entities.

Multi-modality imaging characteristics of costochondral fractures, a highly specific rib fracture for child abuse.

BACKGROUND: Rib fractures in young children are strongly associated with nonaccidental trauma (NAT). Costochondral junction (CCJ) fractures are unique with most being identified in the healing phase on radiographs. NAT-associated CCJ fractures, therefore, may be underdiagnosed. Improved diagnoses of CCJ fractures may lead to better identification of NAT. OBJECTIVE: To document the association of CCJ fractures with NAT, and improve CCJ fracture recognition by documenting the imaging features with multiple radiologic modalities. MATERIALS AND METHODS: Children, ages 0-4 years, with CCJ fractures on radiologic reports were identified over a 10-year period. All available radiographic skeletal surveys, chest radiographs, computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound (US) studies were reviewed. We chose CT as the radiologic gold standard. Imaging patterns of the primary fracture and healing changes were documented. The diagnosis of NAT by the child protective team was documented. RESULTS: One hundred and nine CCJ fractures were found in 22 patients, 21 of whom were diagnosed with NAT (95.5%). Radiographic skeletal survey identified 34.6% of CCJ fractures (P < 0.0001) with a sensitivity of 32.5% and specificity of 99.2%. MRI identified 50.0% of CCJ fractures with a sensitivity of 42.9% and specificity of 98.1%. CONCLUSION: CCJ fractures are highly specific for NAT. As sensitivity is low for radiographic skeletal survey in CCJ fracture diagnosis compared with CT, CT may have a role in confirming a clinical suspicion of NAT.

Fractures of child abuse.

The objective of this paper is to review common challenges when evaluating fractures in the setting of possible child abuse and approaches to navigate them. This paper reviews the variety of imaging modalities available for evaluating child abuse and the advantages/disadvantages of each. Additionally, the authors discuss management of equivocal fractures, including the impact of double-reading skeletal surveys. The complexity of dating the acuity of fractures in young children is discussed. Utilizing the knowledge of fracture type, fracture patterns and patient history, as well as in the setting of cardiopulmonary resuscitation, the authors provide methods for determining the likelihood of abuse.

Magnetic resonance imaging of the fetal gastrointestinal system.

In this paper the authors review the normal imaging appearance of the fetal gastrointestinal tract and patterns of fetal gastrointestinal tract obstruction. The authors include a detailed summary from esophagus to the rectum, including the expected pattern of meconium and small-bowel contents at different gestational ages. Common fetal gastrointestinal tract obstructions are reviewed with accompanying case examples, emphasizing the role of the meconium and bowel-caliber patterns in establishing differential diagnoses. This review also includes imaging pitfalls, complications of gastrointestinal tract obstruction, and implications for patient care.

JOURNAL CLUB: Can Coronal STIR Be Used as Screening for Acute Nontraumatic Hip Pain in Children?

OBJECTIVE: The objective of this study is to evaluate whether coronal STIR MRI can be used as a screening test for nontraumatic acute hip pain in children. MATERIALS AND METHODS: From 2008 to 2012, we identified all patients younger than 18 years at our tertiary care facility who underwent pelvic MRI including coronal STIR for the following indications: acute hip pain, limping, or refusal to bear weight. Patients with a history of trauma were excluded. Each MR image was independently reviewed by four radiologists who were blinded to the clinical outcome. After first reviewing the coronal STIR images only, they then reviewed the full MRI studies in a random order different from that used for review of the coronal STIR images. The sensitivity and specificity of STIR-only images in identifying the presence of abnormality and specific diagnoses were calculated, with the full MRI study considered as the reference standard. Kappa values were calculated for STIR-only and full MRI studies. RESULTS: A total of 127 patients (67 female patients and 60 male patients; median age, 9 years; range, 5 months to 17 years) were identified. The most common abnormalities (calculated as the mean of frequency values noted by four readers) were hip effusion (52%; range, 46-58%), osteomyelitis (42%; range, 29-48%), and myositis (32%; range, 20-40%). For the detection of any abnormality, STIR-only images had a mean sensitivity of 95% and a mean specificity of 67%. For approximately one-third of STIR-only studies with true-positive results, additional abnormalities were found on full MRI studies. CONCLUSION: Coronal STIR imaging of the pelvis has high sensitivity (95%) in the detection of abnormalities associated with acute nontraumatic hip pain in children, but it often misses additional abnormalities.

Frequency and Severity of Acute Allergic-Like Reactions to Intravenously Administered Gadolinium-Based Contrast Media in Children.

OBJECTIVES: The purpose of this study is to determine the frequency and severity of acute allergic-like reactions to gadolinium-based contrast media (GBCM) in children before, during, and after the transition from gadopentetate dimeglumine to gadoterate meglumine as our primary clinical GBCM. MATERIALS AND METHODS: Institutional review board approval was obtained for this Health Insurance Portability and Accountability Act-compliant retrospective investigation. Allergic-like reactions to GBCM in pediatric patients were retrospectively assessed from January 2009 to January 2017, which included a departmental change of GBCM from gadopentetate dimeglumine to gadoterate meglumine. Allergic-like reactions were identified from departmental and hospital databases. The number of doses of GBCM was obtained from billing data. Allergic-like reaction frequencies for each GBCM were calculated and compared using the chi-squared test. RESULTS: A total of 32,365 administrations of GBCM occurred during the study period (327 for gadofosveset trisodium; 672 for gadoxetate disodium; 12,012 for gadoterate meglumine; and 19,354 for gadopentetate dimeglumine). Allergic-like reactions occurred after 21 (0.06%) administrations. Reaction frequencies were not significantly different among the GBCM (0.3% gadofosveset trisodium; 0% gadoxetate disodium, 0.06% gadoterate meglumine, 0.08% gadopentetate dimeglumine; P > 0.05). Ten (47.6%) reactions were mild, 10 (47.6%) were moderate, and 1 (4.8%) was severe. The overall reaction frequency peaked during the 6-month transition period from gadopentetate dimeglumine to gadoterate meglumine (0.20%), compared with 0.07% pretransition (P = 0.048) and 0.04% posttransition (P = 0.0095). CONCLUSION: Allergic-like reactions to GBCM in children are rare. Gadoterate meglumine has a reaction frequency that does not significantly differ from other GBCMs. During the transition from gadopentetate dimeglumine to gadoterate meglumine, an increase in the frequency of reported allergic-like reactions was observed, likely reflective of the Weber effect.