MR imaging of children and young adults with classic findings of osteonecrosis on unenhanced MR images: do contrast-enhanced sequences help?

BACKGROUND

The added value of routine contrast-enhanced MR imaging in children with classic findings of osteonecrosis on unenhanced MR images has not been determined.

OBJECTIVE

Our purpose was to determine the added value of routine contrast-enhanced MR sequences for identifying complications of osteonecrosis.

MATERIAL AND METHODS

Sixty-four patients who underwent 139 contrast-enhanced MR examinations were retrospectively identified. Unenhanced images and subsequently both unenhanced and enhanced images were reviewed in consensus. The location of osteonecrosis and the presence of complicating features (epiphyseal collapse, marrow edema, joint effusion, soft tissue edema) were recorded. Cohen's kappa coefficients (κ) were calculated to assess agreement.

RESULTS

A diagnosis of classic osteonecrosis was made in 22.3% of unenhanced examinations and 28.1% of enhanced examinations (κ = 0.734, P < 0.001). Among patients with complicated osteonecrosis, unenhanced images interpreted without and with contrast-enhanced images showed epiphyseal collapse in 51.2% and 42.5% (κ = 0.796, P < 0.001), marrow edema in 50.4% and 46.8% (κ = 0.727, P < 0.001), joint effusion in 44.9% and 51.2% (κ = 0.686, P < 0.001), and soft tissue edema in 12.2% and 10.1% (κ = 0.674, P < 0.001).

CONCLUSION

The high observed agreement between the unenhanced MR images interpreted without and with contrast-enhanced images shows little marginal benefit from the use of routine contrast-enhanced imaging in children and young adults with classic findings of osteonecrosis on unenhanced MR images.

Imaging features of intravesical urachal cysts in children

BACKGROUND

Urachal cysts, part of the spectrum of congenital urachal anomalies, are typically extrinsic to the urinary bladder.

OBJECTIVE

The purpose of this study is to present the salient imaging features of a pediatric series of unusual intravesical urachal cysts that protrude into the bladder lumen.

MATERIALS AND METHODS

Five children with intravesical urachal cysts depicted on imaging studies were retrospectively identified during a 6-year period at a children's hospital. The clinical charts and findings on ultrasound (US) and voiding cystourethrogram (VCUG) were reviewed.

RESULTS

In all five children, US revealed a thin-walled ovoid cystic structure containing anechoic fluid or echogenic debris and residing along the midline of the anterosuperior aspect of the urinary bladder protruding into the bladder lumen. Histological examination of the partial cystectomy specimen from one child revealed a cystic urachal remnant with intestinal mucosal lining and reactive lymphoid hyperplasia. The cysts in the four other children were managed conservatively without operative intervention.

CONCLUSION

The purpose of this report is to expand the spectrum of urachal remnant anomalies to include these newly recognized intravesical urachal cysts, which are characterized on US by the presence of a thin-walled cyst along the midline anterosuperior aspect of the urinary bladder.

Osteomyelitis and beyond

Musculoskeletal infections are a cause of considerable morbidity in children. Symptoms and signs are often nonspecific, and imaging is needed to define the anatomical location of infected tissue or fluid collections for diagnostic aspiration or biopsy. Prompt diagnosis and precise localization of the infection site has become even more imperative with the emergence and dissemination of highly invasive organisms such as community-acquired Staphylococcus aureus. Although radiography, bone scintigraphy and US continue to play a role, MRI is now the preferred imaging modality for definitive evaluation of pediatric musculoskeletal infections because of its capability of simultaneously assessing the osseous, articular and muscular structures without ionizing radiation exposure. This article focuses on the imaging characteristics of osteomyelitis, septic arthritis and pyomyositis and the differentiating features of potential mimics of infection.

Newer CT applications and their alternatives: what is appropriate in children?

Innovations in image acquisition and reconstruction technologies have greatly expanded the range of CT applications available in the routine clinical setting. CT images of sub-millimeter resolution can now be acquired of entire body regions in a few seconds or even sub-second time, allowing depiction of fine anatomical detail uncompromised by motion artifact. With sophisticated visualization software, image data can be processed into multiplanar, volume-rendered, cine and other formats to better display anatomical abnormalities and facilitate newer applications such as CT angiography, enterography, urography, tracheobronchography and cardiac CT. Newer applications including dual-energy material decomposition CT are furthering the transition of CT from a purely morphological to a combined anatomical, functional and metabolic imaging technique. These newer applications have largely been pioneered in adult populations, and heightened concern of the risk of carcinogenesis from ionizing radiation tempers dissemination of their use in children. Similar information can often be gleaned from alternative imaging modalities without ionizing radiation exposure, such as MRI and US, and what is most appropriate in children will depend on relative diagnostic efficacy, cost, availability and local expertise.

Leukemia and lymphoma

Leukemia and lymphoma are the most common and third most common pediatric malignancies, respectively, and share cell lineages, but the clinical and imaging manifestations of these malignancies vary substantially. Along with providing pertinent details on classification, epidemiology, and treatment, this article reviews the current roles of imaging in the management of childhood leukemia and lymphoma, with attention to diagnosis, staging, risk stratification, therapy response assessment, and surveillance for disease relapse and adverse effects of therapy. Advances in functional imaging are also discussed to provide insights into future applications of imaging in the management of pediatric patients with leukemia and lymphoma.

Infant craniospinal ultrasonography: beyond hemorrhage and hydrocephalus

Ultrasonography is widely used for screening for neonatal intracranial hemorrhage, hydrocephalus, and cord tethering in young infants. Proper interpretation of infant cranial and spinal ultrasound examinations requires not only familiarity with the appearances of these disorders, but also recognition of imaging artifacts capable of mimicking pathology and awareness of developmental variants and conditions that occupy a borderline position along the spectrum from normal to abnormal. This article will review the current understanding of the ultrasonographic characteristics and clinical relevance of these imaging artifacts, developmental variants, and quasi-pathologic conditions to avoid diagnostic pitfalls and guide appropriate patient management.

Imaging of Childhood Interstitial Lung Disease

The aphorism that children are not little adults certainly applies for the imaging of interstitial lung disease. Acquiring motion-free images of fine pulmonary structures at desired lung volumes is much more difficult in children than in adults. Several forms of interstitial lung disease are unique to children, and some forms of interstitial lung disease encountered in adults rarely, if ever, occur in children. Meticulous attention to imaging technique and specialized knowledge are required to properly perform and interpret chest imaging studies obtained for the evaluation of childhood interstitial lung disease (chILD). This review will address technique recommendations for imaging chILD, the salient imaging findings in various forms of chILD, and the efficacy of imaging in the diagnosis and management of chILD.

Multiple ganglion cysts (‘cystic ganglionosis’): an unusual presentation in a child

A case of multifocal and recurrent ganglion cysts is described. An 11-year-old boy was referred because of symptomatic cystic masses in the extremities since the age of 2 years. Over the years, he had experienced intermittent appearance of these lesions, which were associated with pain, but without any systemic manifestations. Magnetic resonance imaging (MRI) showed cystic lesions with synovio-capsular thickening along the temporomandibular joints (TMJ), atlanto-axial synovial articulation, and tendons and joints of the right wrist and hand. Histopathological examination of one lesion showed anastomosing fibro-connective tissue surrounded by a wall of smooth muscle and fibrous connective tissue, findings that were consistent with ganglion cyst. The early onset of the disease, as well as the involvement of multiple and unusual sites, including the TMJ, implies a genetic susceptibility to these lesions that we refer to as 'cystic ganglionosis'.

Liver tumors: pediatric population

Liver tumors in childhood are rare and are typically not detected clinically until they reach a large size and often spread within the organ or metastasize. This can make surgical resection problematic, and almost all of them require extirpation for cure. With very effective chemotherapy for hepatoblastoma and to some extent for sarcomas, many cancers can be shrunk to permit partial hepatectomy, but for most hepatocarcinomas, some of the other malignancies, and even some benign proliferations, their location at the hilum and multiplicity of masses in multiple lobes make transplantation the treatment of choice. Major advances in diagnostic imaging, especially enhanced computed tomography and magnetic resonance imaging, permit a preoperative choice of resection versus transplantation to be achieved in almost all instances, and for the remainder, intraoperative ultrasonography can further help to determine the most desirable approach. The outcome is very much better in the case of hepatoblastoma when transplantation is a primary modality rather than following unsuccessful attempts at resection. In this review, transplantation for liver tumors in children is considered from all aspects, including the importance of screening for tumors whenever possible to avoid the need for transplantation.

Van Wyk and Grumbach syndrome revisited: imaging and clinical findings in pre- and postpubertal girls

BACKGROUND

In 1960 Van Wyk and Grumbach described a syndrome of juvenile hypothyroidism, precocious puberty and ovarian enlargement. These findings undergo complete regression with thyroid hormone replacement therapy. This diagnosis can be made on the basis of imaging findings and thyroid function analysis, avoiding surgery.

OBJECTIVE

To relate the distinctive clinical and imaging features and putative pathophysiological mechanism of a series of patients with Van Wyk and Grumbach syndrome (VWGS).

MATERIALS AND METHODS

Patients with VWGS diagnosed at two large children's hospitals over a 6-year period beginning in 1999 were retrospectively reviewed. A literature review was also conducted.

RESULTS

Five female patients were diagnosed with cystic ovarian enlargement and hypothyroidism at ages ranging from 9 to 17 years. Isosexual precocious puberty was found in prepubescent patients. Associated findings included delayed bone age, ascites, and pleural and pericardial effusions. Ovarian cyst involution occurred following treatment of the hypothyroidism.

CONCLUSION

The association of primary hypothyroidism with cystic ovarian enlargement and precocious puberty is important to recognize. In the absence of suspected ovarian torsion, surgery is unnecessary, as cyst regression occurs after appropriate thyroid hormone replacement. Noncompliance with hormone replacement therapy should be considered when cystic ovarian enlargement is noted in patients with a history of hypothyroidism.

Multimodality imaging of tracheobronchial disorders in children

The trachea and bronchial airways in children are subject to compromise by a number of extrinsic and intrinsic conditions, including congenital, inflammatory, infectious, traumatic, and neoplastic processes. Stridor, wheezing, and respiratory distress are the most common indications for imaging of the airway in children. Frontal and lateral chest and/or neck radiography constitute the initial investigations of choice in most cases. Options for additional imaging include airway fluoroscopy, contrast esophagography, computed tomography (CT), and magnetic resonance (MR) imaging. Advanced imaging techniques such as dynamic airway CT, CT angiography, MR angiography, and cine MR imaging are valuable for providing relevant vascular and functional information in certain settings. Postprocessing techniques such as multiplanar reformatting, volume rendering, and virtual bronchoscopy assist in surgical planning by providing a better representation of three-dimensional anatomy. A systematic approach to imaging the airway based on clinical symptoms and signs is essential for the prompt, safe, and accurate diagnosis of tracheobronchial disorders in children.

Clinical, radiological and pathological features of ABCA3 mutations in children

BACKGROUND

Mutations in the ABCA3 gene can result in fatal surfactant deficiency in term newborn infants and chronic interstitial lung disease in older children. Previous studies on ABCA3 mutations have focused primarily on the genetic abnormalities and reported limited clinical information about the resultant disease. A study was undertaken to analyse systematically the clinical presentation, pulmonary function, diagnostic imaging, pathological features and outcomes of children with ABCA3 mutations.

METHODS

The records of nine children with ABCA3 mutations evaluated at Texas Children's Hospital between 1992 and 2005 were reviewed and their current clinical status updated. Previous diagnostic imaging studies and lung biopsy specimens were re-examined. The results of DNA analyses were confirmed.

RESULTS

Age at symptom onset ranged from birth to 4 years. Cough, crackles, failure to thrive and clubbing were frequent findings. Mean lung function was low but tended to remain static. CT scans commonly revealed ground-glass opacification, septal thickening, parenchymal cysts and pectus excavatum. Histopathological patterns included pulmonary alveolar proteinosis, desquamative interstitial pneumonitis and non-specific interstitial pneumonitis, and varied with age. Dense abnormalities of lamellar bodies, characteristic of ABCA3 mutations, were seen by electron microscopy in all adequate specimens. Outcomes varied with the age at which the severity of lung disease warranted open lung biopsy, and some patients have had prolonged survival without lung transplantation.

CONCLUSIONS

The presentation and course of interstitial lung disease due to ABCA3 mutations are variable, and open lung biopsy and genetic testing are warranted early in the evaluation of children with a consistent clinical picture.

Incomplete Double Aortic Arch with Atresia of the Distal Left Arch: Distinctive Imaging Appearance

OBJECTIVE

We present 10 patients with double aortic arch with atresia of the distal left arch segment, a form of incomplete double aortic arch, and describe the distinct MRI and CT findings for this potentially symptomatic vascular ring.

CONCLUSION

Knowledge of the distinctive imaging appearance of this congenital arch anomaly can direct the radiologist to the correct preoperative diagnosis.

Localization of pleiotrophin and its mRNA in subpopulations of neurons and their corresponding axonal tracts suggests important roles in neural-glial interactions during development and in maturity

Trophic factors are being increasingly recognized as important contributors to growth, differentiation, and maintenance of viability within the mammalian nervous system during development. Pleiotrophin (PTN) is a secreted 18-kDa heparin binding protein that stimulates mitogenesis and angiogenesis and neurite and glial process outgrowth guidance activities in vitro. We localized the sites and time course of expression of the Ptn gene and its protein product in developing and adult mouse nervous system. Expression of the Ptn gene was first observed at embryo day 8.5 (E8.5). At E12.5, transcripts of the Ptn gene were localized in developing neuroepithelium at sites of active cell division in the spinal cord and brain. At E15.5, transcripts were found in the somata of some but not all neurons and glia whereas in the adult its pattern of expression was nearly exclusively restricted to the brain. The PTN protein was found almost entirely in association with the axonal tracts during development and in adults. Furthermore, as opposed to the finding of PTN in both central and peripheral nervous systems during development, PTN was not expressed beyond the exit where axonal tracts become the peripheral nervous system in adults. At all sites and times examined, the somata that contained Ptn transcripts corresponded with the axonal tracts that contained the PTN protein. The results establish that Ptn is expressed in early development at sites of active mitogenesis in developing neuroepithelium and later in both glial cells and neurons at sites of neuronal and glial process formation in developing axonal tracts. The findings establish a correspondence in the localization of PTN within the nervous system at sites of normal developmental processes that correlate with the functional activities of PTN previously described in vitro.

1α,25-Dihydroxyvitamin D(3) down-regulates pleiotrophin messenger RNA expression in osteoblast-like cells

Pleiotrophin (PTN)[heparin-binding-growth-associated molecule (HB-GAM), heparin-binding neurite-promoting factor (HBNF)] is a recently identified polypeptide that stimulates growth of fibroblasts and enhances neurite extension. PTN is expressed in many tissues but relatively high level of expression has been observed in brain and bone. We examined hormonal regulation of PTN mRNA expression in several osteoblast-like cell lines including MC3T3-E1 and ROS17/2.8. The levels of PTN mRNA in these cells was significantly reduced by treatment with 10(-8) M: 1α,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) for 24 h. However, PTN mRNA levels were increased when the non-osteoblastic cell line, ROS 25/1, was treated with 1,25(OH)(2)D(3). These effects were observed in a dose-dependent manner in a dose range between 10(-11) M: to 10(-8) M: . This effect was specific to 1,25(OH)(2)D(3), since PTN mRNA levels were not affected by other steroids such as retinoic acid and dexamethasone in MC3T3-E1 or ROS17/2.8 cells. Similar 1,25(OH)(2)D(3) down-regulation of PTN mRNA was also observed in primary cultures of osteoblast-enriched fetal rat calvaria cells as well as cultures of MC3T3-E1 and ROS17/2.8 cells. These observations suggest that PTN expression in osteoblasts is regulated by the calcitropic hormone, 1,25(OH)(2)D(3), and that PTN may play a role in vitamin D-dependent regulation of bone metabolism.