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OBJECTIVE: Body composition is associated with metablic factors in adults; however, data are limited regarding obese children. This study was undertaken to assess body composition, regional fat distribution, and metabolic factors in obese 6-18-y-old children and adolescents. DESIGN: Cross-sectional assessment. SUBJECTS: Thirty-six obese children and adolescents, (mean+/-s.e.m.) age 11.8+/-0.5 y, BMI 34.1+/-1.2 kg/m(2). MEASUREMENTS: Body composition was assessed by dual energy X-ray absorptiometry and computerized tomography. Fasting insulin, glucose and leptin levels, and the homeostasis model assessment of insulin sensitivity (HOMA-IR) were assessed. RESULTS: The girls had significantly lower glucose levels than the boys. The ethnic group differences (African American children vs white children) in fat mass, total CT fat, subcutaneous CT fat, insulin level, leptin level, and higher HOMA-IR were not significant after adjusting for age or pubertal stage. These differences in abdominal fat and subcutaneous abdominal fat were also not independent of total body fat or BMI. No ethnic group differences in visceral abdominal fat were noted. Insulin level and HOMA IR were associated with leptin level (independent of fat mass) and fat mass. Leptin level was associated with fat mass, total CT fat, and subcutaneous CT fat; however the associations between the CT fat measures and leptin were not independent of total body fat mass. CONCLUSIONS: Neither visceral abdominal fat, subcutaneous abdominal fat, insulin levels, or insulin resistance differed by ethnic group when adjusted for age or pubertal status. This contrasts with findings in adults and non-obese children which suggest lower levels of visceral fat and higher insulin levels and insulin resistance in African American children and adolescents.

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MR imaging plays a valuable role in the evaluation of foot and ankle in infants and children. In young children with nonossified bones, MR imaging offers the advantage of effectively demonstrating the cartilaginous anlage in addition to soft tissue and bone marrow. The MR imaging examination is tailored to the clinical question, the child's age, foot size, and ability to cooperate. This article reviews the MR imaging of a number of familiar and uncommon disorders of the pediatric foot and ankle.

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Imaging pediatric foot disorders is a challenging task. Optimally exposed and well-positioned radiographs can answer many questions. Because many bones may not be completely ossified, however, CT or MR imaging is often needed to provide additional information to assist in the management of congenital and acquired lesions in the foot.

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Ultrafast MRI sequences have changed the use of MRI for evaluating fetal abnormalities. Currently, the best application is the demonstration of normal fetal brain development and the further definition of suspected brain abnormalities found on ultrasound. MRI differentiates well the various types of fetal ventriculomegaly. Superior posterior fossa visualization allows differentiation of Dandy Walker malformation from a large cisterna magna. Anomalies of the corpus callosum and some disorders of neuronal migration can be seen. MRI is also valuable in the evaluation of fetal giant neck masses for planning delivery of the baby and surgery for life threatening airway obstruction. In the chest, MRI differentiates masses such as diaphragmatic hernia, cystic adenomatoid malformation and sequestration, and aids in planning fetal surgery because MRI directly visualizes the position of the lung, liver and bowel. MRI defines abnormalities of the urinary tract by demonstrating dysplastic pathology in the renal cortex and dilation of the collecting systems. Oligohydramnios does not effect MRI.

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OBJECTIVE: The purpose of our study was to determine if a standard imaging protocol using ultrafast MR sequences could adequately reveal normal posterior fossa anatomy in fetuses and, if so, to document a template on MR imaging for normal posterior fossa development. MATERIALS AND METHODS: A retrospective review found 66 MR imaging studies of 63 fetuses, 16-39 weeks' gestation age (mean, 25 weeks' gestation), who were referred between June 1996 and May 1999 for evaluation of non-central nervous system anomalies revealed on prenatal sonography. All fetuses had normal brains and spines on prenatal sonography. The standard MR imaging protocol included axial, sagittal, and coronal half-Fourier acquisition single-shot turbo spin echo (HASTE); sagittal and coronal two-dimensional fast low-angle shot (FLASH); and axial turbo T1-weighted FLASH images through the fetal brain. Structures that we analyzed were the fourth ventricle, the cisterna magna, the vermis, the cerebellar hemispheres, and the brainstem. Using the HASTE sequences, we documented gestational age-specific signal intensity changes in the cerebellar hemispheres and the brainstem. RESULTS: The posterior fossa anatomy was sufficiently well defined to exclude abnormalities of the fourth ventricle and cerebellar vermis in all cases. Because of high T2-weighting, good contrast enhancement, and good signal-to-noise ratios, HASTE images provided the best anatomic definition of the posterior fossa. CONCLUSION: Normal posterior fossa anatomy can be adequately shown on ultrafast MR images, which can be helpful when prenatal sonography is equivocal.

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Pediatric thoracic vascular abnormalities include many anatomic variants and pathologic conditions. Although some vascular variants are inconsequential and are discovered incidentally on imaging studies, several anomalies have profound effects on the airway and pulmonary parenchyma. Imaging plays a key role in evaluating the chest and its vasculature. The chest radiograph is usually the first screening study performed during the course of evaluation for a vascular abnormality. Cross-sectional imaging with CT and magnetic resonance imaging provides precise anatomic information and has in most cases replaced invasive diagnostic angiographic procedures. We describe common thoracic vascular abnormalities that occur in children and the imaging techniques currently used in their evaluation.

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BACKGROUND: During the course of our routine renal ultrasound examinations, we noticed that some children who developed dilatation of a renal pelvis following voiding had reflux found on voiding cystourethrography (VCUG). PURPOSE: To determine if increase in renal pelvic size on post-void ultrasound is an accurate predictor of vesicoureteral reflux. MATERIALS AND METHODS: Fifty-seven children (113 kidneys) underwent renal ultrasound and VCUG on the same day. Anteroposterior dimensions of the renal pelves were prospectively measured on ultrasound prior to and following patient voiding and correlated with the results of the VCUG. RESULTS: The diameter of the renal pelvis increased in 12 and decreased in 38 kidneys on post-void ultrasound. Vesicoureteral reflux occurred in 19 kidneys and among these kidneys, renal pelvic diameter increased in 2, decreased in 7, and was unchanged in 10 following voiding. There was no significant correlation between post-void change in renal pelvic diameter and the presence of vesicoureteral reflux. CONCLUSION: Increase in renal pelvic size on post-void ultrasound is not a reliable indicator of vesicoureteral reflux.

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The development of ultrafast magnetic resonance imaging scanners and sequences provides a new tool for the diagnosis of fetal anomalies. Magnetic resonance imaging is a valuable adjunct to prenatal ultrasound especially for the evaluation of suspected fetal brain anomalies, chest masses, abdominal masses, and renal diseases.

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Beyond basic screening chest radiographs, modern cross-sectional imaging with computed tomography and magnetic resonance imaging demonstrates more detailed anatomic and pathologic information than previously possible. This information is important if it influences decision-making during patient care and management and adds to the understanding of disease processes. In this article we review recent developments in computed tomography and magnetic resonance imaging, advantages and limitations of these techniques in the pediatric chest, and the role of cross-sectional imaging in a series of selected pulmonary topics. In the process, we provide a brief preview of future pediatric pulmonary imaging developments.

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Advances in perinatal medicine and neonatology have dramatically changed clinical outcomes for premature neonates and have ushered in a new era of radiological complexity. "Portable" chest radiographs continue to be the mainstay in diagnostic imaging of fragile newborns, but radiologists may be confronted with new and unexpected radiological expressions of once-familiar disease processes. Familiarity with the radiological impact of emerging treatments in premature neonates is essential for accurate film interpretation.

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Magnetic resonance imaging is an established technique for imaging the shoulder because it demonstrates clearly the articular surfaces, medullary canal and the extra-articular soft tissues which can be affected in shoulder disorders. The value of MR imaging in the evaluation of the traumatized shoulder has been described [1]; however, few cases of MR imaging in nontraumatic disorders in children have been reported. We reviewed the findings in 55 children undergoing MRI of the shoulder for nontraumatic conditions and included selected cases showing a broad range of imaging findings.

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Compression of the airway by the innominate artery has been a controversial cause of stridor and apnea in infants. Magnetic resonance imaging has been applied to document the possible association of segmental tracheomalacia. Forty infants with symptoms of stridor were studied, 7 of 40 infants aged 3-21 months (mean 10 months) had innominate artery compression on the trachea. Five infants were treated conservatively and two infants underwent surgery. Flattening of the trachea was longer than the mass compression point by the innominate artery. Therefore, intrinsic abnormality of the trachea is the basis of the respiratory symptom.

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Ovarian torsion is uncommon and has a nonspecific clinical presentation. To determine the impact of imaging on clinical management, the authors reviewed their recent experience with 12 children who had a total of 13 episodes of ovarian torsion. Three children presented as neonates, six were premenarchal, and three were postmenarchal. Ultrasound was the imaging study of choice. In all three neonates, ultrasonography showed complex abdominopelvic cysts indicating the need for surgery. In five of 10 episodes in older patients, ultrasonography showed a solid mass with an appearance strongly suggestive of torsion. Same-day surgery was performed in three patients, and the involved ovary was salvaged in one. Another patient had a small piece of normal-appearing ovary left in situ. This low rate of ovarian salvage is attributable to the combination of delay in patient presentation and surgical delay owing to the often nonspecific clinical and imaging presentation of ovarian torsion. A high level of clinical suspicion, expeditious imaging, and familiarity with the varied clinical and imaging presentations of ovarian torsion should decrease the surgical delay and improve the likelihood of ovarian salvage.

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Radiologic images and medical records of 42 children with Langerhans cell histiocytosis (LCH) (histiocytosis X) were reviewed to evaluate the presentation of the disease and the evolution of the radiologic findings. There were 26 male and 16 female patients aged 3 months to 18 years. Twenty-two patients presented with localized disease; 20 presented with multifocal disease. Four patients developed diabetes insipidus. Two patients had organ dysfunction. The radiologic findings were largely due to destructive bone lesions; 83% of the patients had at least one affected bone. Isolated soft-tissue masses, interstitial lung disease, and central nervous system abnormalities were also seen. Of patients in whom results of appropriate follow-up were available, 91% showed improvement in their lesions, 43% developed new lesions, and 92% had good clinical outcomes. LCH is usually a self-limited disease with a varied clinical and radiologic presentation. The prognosis is generally poor in children with organ dysfunction. In the absence of organ dysfunction, children with either localized or multifocal LCH have an excellent prognosis.

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Accurate diagnosis is important in the evaluation of airway disorders of infants and children. Today, multiple imaging techniques are available to evaluate the pediatric airway. We performed magnetic resonance (MR) imaging of the airway in 16 infants and children with symptoms of airway obstruction. Fourteen of 16 patients symptoms were related to compression of the airway by vascular structure. MR imaging was useful in the diagnosis and management of these patients without the need for more invasive procedures.

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