The paediatric thymus: recognising normal and ectopic thymic tissue.

The appearance of the paediatric thymus changes as the normal process of thymic involution occurs. Thymic tissue may be orthotopic within the anterior mediastinum or ectopically located along the course of its embryological development. The variable appearance of orthotopic and ectopic thymic tissue in children on imaging studies may lead to misinterpretation of the normal thymus as pathology. Recognition of normal thymic tissue can mitigate unnecessary further diagnostic testing and patient anxiety. In this review, we discuss the embryological development and anatomical variants of normal thymus, and demonstrate the multimodality imaging features of the normal thymus in children, including positron-emission tomography, and diffusion-weighted imaging and in- and opposed-phase imaging on magnetic resonance imaging. We demonstrate the normal thymus mimicking pathological processes and discuss features that distinguish normal thymus, including thymic rebound hyperplasia, from pathology.

EURAMOS-1, an international randomised study for osteosarcoma: results from pre-randomisation treatment.

BACKGROUND: Four international study groups undertook a large study in resectable osteosarcoma, which included two randomised controlled trials, to determine the effect on survival of changing post-operative chemotherapy based on histological response. PATIENTS AND METHODS: Patients with resectable osteosarcoma aged ≤40 years were treated with the MAP regimen, comprising pre-operatively of two 5-week cycles of cisplatin 120 mg/m(2), doxorubicin 75 mg/m(2), methotrexate 12 g/m(2) × 2 (MAP) and post-operatively two further cycles of MAP and two cycles of just MA. Patients were randomised after surgery. Those with ≥10% viable tumour in the resected specimen received MAP or MAP with ifosfamide and etoposide. Those with <10% viable tumour were allocated to MAP or MAP followed by pegylated interferon. Longitudinal evaluation of quality of life was undertaken. RESULTS: Recruitment was completed to the largest osteosarcoma study to date in 75 months. Commencing March 2005, 2260 patients were registered from 326 centres across 17 countries. About 1334 of 2260 registered patients (59%) were randomised. Pre-operative chemotherapy was completed according to protocol in 94%. Grade 3-4 neutropenia affected 83% of cycles and 59% were complicated by infection. There were three (0.13%) deaths related to pre-operative chemotherapy. At definitive surgery, 50% of patients had at least 90% necrosis in the resected specimen. CONCLUSIONS: New models of collaboration are required to successfully conduct trials to improve outcomes of patients with rare cancers; EURAMOS-1 demonstrates achievability. Considerable regulatory, financial and operational challenges must be overcome to develop similar studies in the future. The trial is registered as NCT00134030 and ISRCTN 67613327.

Anatomical distribution of vertebral fractures: comparison of pediatric and adult spines.

SUMMARY: We compared the distribution of vertebral fractures in adults and children and found that fractures occurred in different locations in the two age groups. This likely relates to the different shape of the immature spine. INTRODUCTION: We hypothesized that the anatomical distribution of vertebral fractures (VF) would be different in children compared to adults. METHODS: We compared the distribution of VF defined using the Genant semi-quantitative method (GSQ method) in adults (N = 221; 545 fractures) and in children early in the course of glucocorticoid therapy (N = 44; 94 fractures). RESULTS: The average age in the adult cohort was 62.9 years (standard deviation (SD), 13.4 years), 26% was male, the mean lumbar spine Z-score was -1.0 (SD, 1.5), and the corresponding T-score was -2.4 (SD, 1.4). The pediatric cohort median age was 7.7 years (range, 2.1-16.6 years), the mean lumbar spine Z-score was -1.7 (SD, 1.5), 52% was male, and disease categories were acute lymphoblastic leukemia (66%), rheumatological conditions (21%), and nephrotic syndrome (14%). The VF distribution was biphasic in both populations, but the peaks differed in location. In adults, the peaks were at T7/T8 and at T12/L1. In children, the focus was higher in the thoracic spine, at T6/T7, and lower in the lumbar spine, at L1/L2. When children were assessed in two age-defined sub-groups, a biphasic VF distribution was seen in both, but the upward shift of the thoracic focus to T6 was observed only in the older group, with the highest rates of fracture present between ages 7 and 10 years. CONCLUSIONS: These results suggest that the anatomical distribution of VF differs between children and adults, perhaps relating to the different shape of the immature spine, notably the changing ratio of kyphosis to lordosis.

Simultaneously Acquired MRI Arterial Spin-Labeling and Interictal FDG-PET Improves Diagnosis of Pediatric Temporal Lobe Epilepsy.

BACKGROUND AND PURPOSE: Interictal FDG-PET scans are a routine diagnostic technique for the identification of epileptogenic foci in the presurgical work-up of medically refractory pediatric epilepsy. With the advent of PET/MR imaging, it has become possible to simultaneously acquire FDG-PET and arterial spin-labeling perfusion data. The objective of this study was to evaluate whether the incorporation of arterial spin-labeling data with interictal FDG-PET could improve the diagnostic performance metrics of FDG-PET for identification of epileptogenic foci. MATERIALS AND METHODS: Forty-five pediatric patients with a mean age of 10.8 years were retrospectively included in this study. These patients all underwent PET/MR imaging to diagnose suspected focal epilepsy. RESULTS: When compared to interpretations of interictal FDG findings alone, FDG combined with arterial spin-labeling findings resulted in significantly decreased sensitivity (0.64 versus 0.52, P = .02), significantly increased specificity (0.50 versus 0.75, P = .04), and an increased positive predictive value (0.59 versus 0.75). The decreased sensitivity was found to be primarily driven by patients with extratemporal lobe epilepsy, as a subgroup analysis showed decreased sensitivity for patients with extratemporal epilepsy (0.52 versus 0.38, P = .04), but not for temporal epilepsy (0.83 versus 0.75, P = .16). Additionally, substantial agreement between focal FDG hypometabolism and arterial spin-labeling hypoperfusion was demonstrated with the Cohen κ (0.70, P < .01). CONCLUSIONS: These findings suggest that simultaneously acquired interictal FDG-PET and arterial spin-labeling data can improve the diagnosis of epileptogenic foci, especially in the setting of temporal lobe epilepsy where they improve specificity and positive predictive value, with preservation of sensitivity.

Effects of citrus and avocado irrigation and nitrogen-form soil amendment on host selection by adult Homalodisca vitripennis (Hemiptera: Cicadellidae).

Host plant water status is thought to influence dispersal of the xylophagous leafhopper Homalodisca vitripennis Germar, especially where plants are grown under high evaporative demand. Preference by adult H. vitripennis for plants grown under different water deficit and nitrogen form fertilization regimens was studied under laboratory conditions. Leafhopper abundance and ovipositional preference were studied on potted 'Washington navel' orange and 'Haas' avocado in cage choice tests, and feeding rate was estimated using excreta produced by insects confined on plants. A similar study compared responses to citrus treated with 1:1 and 26:1 ratios of fertigated nitrate-N to ammonium-N. The insects were more abundant, oviposited, and fed significantly more on surplus-irrigated plants than on plants under moderate continuous deficit irrigation except avocado feeding, which was nearly significant. Plants exposed to drought became less preferred after 3 and 7 d in avocado and citrus, respectively. Citrus xylem fluid tension at this point was estimated at 0.93 MPa. A corresponding pattern of decline in feeding rate was observed on citrus, but on avocado, feeding rate was low overall and not statistically different between treatments. No statistical differences in abundance, oviposition, or feeding were detected on citrus fertigated with 26:1 or 1:1 ratios of nitrate-N to ammonium-N. Feeding occurred diurnally on both plant species. Discussion is provided on the potential deployment of regulated deficit irrigation to manage H. vitripennis movement as part of a multitactic effort to minimize the risk of disease outbreaks from Xylella fastidiosa Wells et al. in southern California agriculture.

Thallium-201 for oncological imaging in children.

Many pediatric centers are beginning to accumulate a large experience in the use of thallium-201 (201Tl) imaging with 201Tl requires a state-of-the-art high-resolution gamma camera computer system with single photon emission computed tomography (SPECT) capability and a physician-directed tailored examination. Tumor imaging with 201Tl, with its multifactorial localization mechanisms that are different from those for gallium-67, offers a distinct advantage over gallium tumor imaging with a short total imaging time. Tumors are variable in avidity and intensity of thallium uptake. Primary and metastatic disease can be detected with 201Tl scintigraphy. Baseline pretreatment determination of thallium avidity is crucial to its efficacy in therapeutic response assessment. Adjunctive SPECT imaging provides greater sensitivity for lesion detection and direct comparison of physiology (thallium uptake) with anatomy (computed tomography and magnetic resonance imaging). The sensitivity and specificity for detection of pediatric brain tumors has been reported as 77% and 93%, respectively. Thallium-201 brain SPECT also provides a less expensive and more readily available alternative to positron emission tomography for assessing the functional state of pediatric brain tumors. Extremity osteogenic sarcoma and Ewing's sarcoma have 100% sensitivity for 201Tl uptake pretreatment. Early results confirm an association between 201Tl uptake and histological tumor response. The determination of residual/recurrent disease versus thymic rebound and other nonneoplastic change in thallium-avid lymphoma, rhabdomyosarcoma, and germ cell tumors that involve the thorax can be confirmed with a 201Tl SPECT examination. Soft-tissue tumors elsewhere in the body may be detected with 201Tl scintigraphy. Thallium-201 does not exhibit 100% specificity for tumors. False-positive 201Tl uptake has been seen in histiocytosis X, benign bone tumors, stress fractures, and inflammation.

Hepatobiliary scintigraphy in children.

Hepatobiliary scintigraphy using iminodiacetic (IDA) radiopharmaceuticals provides clinically useful information on the function of the biliary tract in a variety of pathological processes in children, including neonatal jaundice, gallbladder dysfunction, trauma, and liver transplantation. Phenobarbital premedication (5 mg/kg per day for a minimum of 5 days in divided doses) is used in infants who are being examined for neonatal jaundice to increase the accuracy of 99mTc-IDA scintigraphy in differentiating extrahepatic biliary atresia from neonatal hepatitis. Biliary atresia can be ruled out in an infant if a patent biliary tree is shown with passage of activity into the bowel. If no radiopharmaceutical is noted in the bowel on imaging up to 24 hours, distinction between severe hepatocellular disease and biliary atresia cannot be made. The literature reports 91% accuracy, 97% sensitivity, and 82% specificity for hepatobiliary imaging in the diagnosis of biliary atresia. The impairment of both intrahepatic and extrahepatic biliary drainage is an important cause of liver disease in cystic fibrosis. Hepatobiliary scintigraphy in cystic fibrosis has shown characteristic patterns of dilatation of mainly the left hepatic duct, narrowing of the distal common bile duct, gallbladder dysfunction, and delayed bowel transit. Cholecystitis in children may be acalculous. Sensitivity and specificity for the scintigraphic diagnosis of acute acalculous cholecystitis is reported to range from 68% to 93% and 38% to 93%, respectively. Cholescintigraphy in a suspected bile leak provides information generally not available with other techniques, except for direct cholangiography. If the amount of intraperitoneal accumulation of the tracer is greater than that entering the gastrointestinal tract, surgery is usually indicated. Hepatobiliary imaging in children who have undergone liver transplantation will assess graft vascularity, parenchymal function, biliary drainage, presence of a leak, and obstruction.

Effect of cimetidine on delta-aminolevulinic acid synthase and microsomal heme oxygenase in rat liver.

Cimetidine is a well known inhibitor of the heme-containing enzyme cytochrome P-450. We have found that it also inhibits delta-aminolevulinic acid synthase (ALA-S) and microsomal heme oxygenase, the rate-limiting enzymes for heme synthesis and heme degradation respectively. Cytochrome P-450 content was decreased but microsomal heme concentration remained unaltered for a period of 30 min after in vivo cimetidine administration to rats. In vitro incubation of cimetidine with each of the above enzymes revealed no direct effect of cimetidine on ALA-S but about 50% inhibition of heme oxygenase and 20% reduction in cytochrome P-450 content. This suggests that a metabolite of cimetidine inhibits ALA-S activity in vivo, while the drug itself or a metabolite inhibits heme oxygenase both in vivo and in vitro. A rise in ALA-S activity seen after its early inhibition and its return to approximate control values after 60 min suggest a reversible inhibition of ALA-S by a metabolite of cimetidine and may correspond to its clearance from the animal. An elevation in microsomal heme content paralleled the rise in ALA-S activity while microsomal heme oxygenase activity returned to only 65% of control value 60 min after cimetidine treatment. Cytochrome P-450 content did not change after its initial decrease, suggesting that irreversible alteration had occurred.

Lung volumes, mechanics, and perfusion after pulmonary resection in infancy.

Partial pulmonary resection in early childhood is well tolerated. Although long-term outcome has been described in several follow-up studies, almost no information is available on postoperative lung perfusion. We studied 14 patients 3 to 20 years (mean, 11.6 years) after they underwent partial pulmonary resection at 1 week to 30 months of age (mean, 6.8 months). We examined development, pulmonary function, endurance, radiographs and ventilation-perfusion scans. We used predicted pulmonary function test values, which were corrected for the relative amount of lung removed and called predicted-corrected values. We hypothesized that the remaining lung would have altered ventilation-perfusion characteristics. We found no abnormalities in the patients' physical development. Most children had abnormal regional ventilation, but normal equilibration occurred; five patients had gas retention; all had decreased perfusion to the area of resection; nine patients showed ventilation-perfusion mismatch characterized by dead-space ventilation. Lung volumes were within the predicted range in 12 patients. Residual volume and functional residual capacity were larger than predicted-corrected values in most patients but residual volume in relation to total lung capacity was at or below normal in 6 of 11 and did not correlate with the amount of lung removed. Most patients had prolonged expiratory flows. We conclude that lung resection in early childhood leads to good functional recovery. However, decreased expiratory flows, regional ventilation abnormalities, and decreased perfusion suggest dysplastic parenchyma and vascular bed in the area of resection.

The cycle of violence and victimization: a study of the school-based intervention of a multidisciplinary youth violence-prevention program.

This article reports on the school-based intervention component of a multidisciplinary program intended to reduce and prevent youth violence in the East New York neighborhood of Brooklyn. This intervention is based on three theories. The first theory posits that modifying beliefs, attitudes, and norms will help youths develop behaviors that support nonviolence. The second theoretical construct asserts that enhancing relationships with peers and family will buffer youths from the effects of exposure to violence. Finally, the third theory suggests that changing aspects of the setting and climate that contribute to violent behavior will prevent violence. The school-based intervention, the Safe Harbor, is a victim-assistance and violence-prevention program. The Safe Harbor offers activities including a 20-lesson violence-prevention and victim-assistance curriculum, counseling, parent involvement, teacher training, and school-change campaigns. The evaluation design is a panel study, with cohorts surveyed longitudinally at nonequivalent intervals. One hundred and fifteen seventh- and eighth-grade students who receive the curriculum and other services are the experimental group; the other 879 students in the seventh and eighth grades serve as the comparison group. Baseline data were collected through a survey of the entire school before the program's implementation in January 1995. Subsequent data collection will include interviews and focus groups; future analysis will address how participation in other parts of the Safe Harbor program or other programs in the school affects outcomes. The participation rate for the baseline survey in the experimental group was 86%, in the comparison group 76%. Responses to the survey questions were virtually identical between the two groups. Preliminary analyses reflect a climate of pervasive violence in the school, family, and community. More than half of the sample reported witnessing a severe beating in the school or their community within the past four months. Forty-four percent witnessed someone being attacked with a weapon in their neighborhood. The psychological consequences of exposure to violence were severe-51% of the sample reported post-traumatic stress disorder (PTSD) symptoms. A number of lessons have been learned from implementing and evaluating this project, including the importance of fostering community partnership and strong relationships with the school, and addressing both reactions to victimization and norms and beliefs about aggression.

Nuclear medicine topics in pediatric musculoskeletal disease: techniques and applications.

Musculoskeletal scintigraphy has excellent sensitivity for the evaluation of benign disease in children. Using illustrative cases, a spectrum of techniques and applications of nuclear medicine studies for benign bone diseases are presented. An approach to the use and evaluation of bone density evaluation in children also is discussed.

Angiographic demonstration of congenital absence of both internal carotid arteries. Case report.

The authors present angiographic demonstration of bilateral, congenital, total absence of the internal carotid arteries in a patient with subarachnoid hemorrhage. Angiography demonstrated complete absence of both internal carotid arteries. The intracranial blood supply had been provided by communication between a hypertrophied basilar artery and the circle of Willis through the posterior communicating arteries. An aneurysm, believed to be the site of the subarachnoid hemorrhage, arose from the basilar artery. Absence of the carotid canals substantiated the congenital nature of the anomaly. The related embryology is reviewed.

B mode ultrasonography--spectrum of paediatric ocular disease.

BACKGROUND: Despite having appropriate sonographic equipment available many radiologists remain unfamiliar with B mode sonography of the eye. OBJECTIVE: This article reviews the advantages and disadvantages of B mode sonography of the paediatric eye. We illustrate the spectrum of eye abnormalities occurring in paediatric practice and the sonographic appearance of clinical entities for which sonography is appropriate. MATERIALS AND METHOD: We reviewed our experience of eye sonography within a paediatric radiology department over 8 years. A total of 212 sonographic examinations were performed on 206 eyes in 103 children, aged from 3 days to 16 years (mean 4.6 years). RESULTS: Sonography was well tolerated by the children, was a very useful imaging modality and was the only diagnostic imaging modality required in 94%. Supplementary computed tomography (CT) was performed in ten of 206 eyes (5%) and magnetic resonance imaging (MR) was performed in two of 206 eyes (1%). CONCLUSIONS: B mode sonography is a very useful imaging modality for suspected ocular or orbital pathology in children and is often the appropriate first line investigation following clinical evaluation. Radiologists familiar with sonography of the eye can provide valuable support to their ophthalmology colleagues.

Cimetidine suppresses chemically induced experimental hepatic porphyria.

The ability of cimetidine to reduce the activity of hepatic aminolevulinic acid synthase (ALA-S) was examined in allylisopropyl acetamide (AIA) treated porphyric adult rats. A dose of 20 mg cimetidine/100 gm body weight resulted in a 50% decrease in the AIA-induced hepatic ALA-S activity compared to rats treated with AIA alone. Heme oxygenase activity was decreased 25% compared to rats treated with AIA alone. The effects of AIA and cimetidine on cytochrome P-450 were not additive, suggesting competition for a common site of interaction. The results suggest that cimetidine may prove to be useful in treating porphyria in humans.

Laparoscopy as a cause of a false-positive Meckel's scan.

A new cause of a false-positive result of a Meckel's scan is reported. An 11-year-old girl had a 3-week history of constant right lower quadrant pain that was initially managed by laparoscopic appendectomy. A repeated laparoscopy for persistent pain was nondiagnostic. A missed Meckel's diverticulum was considered as the cause of this pain, which prompted a Meckel scan. This scan revealed a periumbilical focus of activity that was interpreted as a Meckel's diverticulum attached to the anterior abdominal wall by a band. The laparotomy showed no Meckel's diverticulum. The false-positive result of the Meckel scan may be the result of inflammation from the periumbilical laparoscopic port site.

Nematodes Associated with Fig Wasps, Pegoscapus spp. (Agaonidae), and Syconia of Native Floridian Figs (Ficus spp.).

Syconia in successive developmental phases from Ficus laevigata Vahl (F. citrifolia Miller sensu DeWolf 1960) (Moraceae) and successive life stages of its fig wasp pollinator, Pegoscapus sp. (P. assuetus (Grandi) sensu Wiebes 1983) (Agaonidae) were dissected to elucidate their association with two undescribed species of nematodes. Parasitodiplogazter sp. (Diplogasteridae) are transported by female Pegoscapus sp. into the cavity of a phase B syconium as third-stage juveniles (J3), where they molt to the J4 stage and greatly increase in size in the hemocoel of the fig wasp after it begins to pollinate and oviposit in female florets. The J4 exit the wasp cadaver in a phase B or early phase C syconium, and molt to adults that mate and lay eggs. New J3 infect the next generation of female or male wasps as they emerge from their galls in phase D figs. Mated entomogenous females of Schistonchus sp. (Aphelenchoididae) are transported in the hemocoel of female wasps to the fig cavity of a phase B syconium. Female Schistonchus sp. exit the wasp and parasitize immature male florets causing an exudate, the development of hypertrophied epidermal cells of the anther filaments and anthers, and aberrations of the anther filament, anthers, and pollen. At least one generation of Schistonchus sp. occurs in the male florets. Entomogenous females appear at about the time that fig wasps molt to adults in their galls in late phase C syconia. Another Schistonchus sp. was recovered from females of P. mexicanus (Ashmead) (P. jimenezi (Grandi) sensu Wiebes 1983) and from the syconia of F. aurea Nuttall and appears to have a life cycle similar to that described for the Schistonchus sp. from F. laevigata.

Formulary conversion from glipizide to glyburide: a cost-minimization analysis.

Economic pressure prompted us to search for and implement cost-saving strategies at Bronx Municipal Hospital. This paper describes a cost-minimization analysis of the impact of formulary substitution of glyburide for glipizide on glycemic control, safety, and costs. In 76 patients with computerized prescription records, switching from a mean daily glipizide dose of 19 mg to a mean daily glyburide dose of 10.2 mg did not affect glycemic control. A subset of 33 elderly patients experienced only three drug-related adverse events during the 2-year observation period. The conversion program yielded a 51% reduction in overall expenditures for oral hypoglycemic agents between 1991 and 1993. These findings indicate that our conversion program was successful, which has led to its becoming a model for other New York City municipal outpatient pharmacies.

Pediatric radiologic imaging.

Medical imaging in the pediatric age group presents special problems. The modern pediatric radiology department is a specialized area, and ensuring an adequate examination requires meticulous care from technician, radiologist and referring clinician. Radiation dose must be kept to a minimum, and constant modifications are being made to the "routine" methods of investigating common problems. These modifications include the introduction and rational integration of all the newer modalities. This presentation offers a modern diagnostic approach to a variety of common pediatric clinical problems.