Iodixanol pharmacokinetics in children

The objective of this report was to study the elimination pharmacokinetics of iodixanol in children. Iodixanol (Visipaque, Nycomed Inc., Wayne, PA, USA) is a new iso-osmolar iodinated radiocontrast agent. We hypothesized that elimination of this agent would be dependent on age-related differences in renal clearance. Seven centers enrolled 43 patients. Cardiac catheterization was performed in 41 patients and cranial computed tomography in 2. Patients were entered into 5 age groups: newborn to <2 months, 2 to <6 months, 6 months to <1 year, 1 to <3 years, and 3 to <or=12 years. Plasma samples were obtained before and at 4 time periods after completion of iodixanol injection: 0.75-1.25 hours, 2-4 hours, 8-12 hours, and 16-32 hours. Plasma concentrations of iodixanol were determined using high performance liquid chromatography. The primary pharmacokinetic endpoint was the terminal elimination rate constant (kel). Data were complete for 40 patients, showing mean kel significantly lower in newborn to <2-month-old patients vs older patients: (h-1, mean +/- standard deviation [SD]): newborn to <2 months 0.185 +/- 0.060, 2 to <6 months, 0.256 +/- 0.046, 6 months to <1 year 0.299 +/- 0.042, 1 to <3 years 0.322 +/- 0.058, and 3 to <or=12 years 0.307 +/- 0.071; with increasing age, excretion is more rapid, as shown by each age group's elimination half-life (t1/2 beta) (h) 4.14 +/- 1.41, 2.79 +/- 0.55, 2.36 +/- 0.37, 2.23 +/- 0.51, and 2.36 +/- 0.52, respectively. Iodixanol has elimination in children >6 months of age that is comparable to normal adults. Prolonged elimination in children <6 months of age is related to renal immaturity.

Hepatoblastoma with spinal metastases

Spinal cord compression secondary to metastases is an infrequent complication of childhood cancer. We describe an infant with hepatoblastoma in whom cord compression developed because of extensive epidural metastases during treatment. This is a hitherto undescribed metastatic site for hepatoblastoma.

Hemoperitoneum and disseminated intravascular coagulation in two neonates with congenital bilateral neuroblastoma

We report two neonates with anemia, hemoperitoneum, and bilateral palpable abdominal masses. Both developed bleeding: a hemoperitoneum in one and visceral hemorrhages secondary to disseminated intravascular coagulation in the other. Each child was thought to have an unusual complication of adrenal hemorrhage, as the masses were of mixed echogenicity. However, histological evaluation revealed neuroblastoma. These cases point out the diagnostic dilemma of a mixed echogenicity suprarenal mass in the neonatal period and emphasize that local and disseminated bleeding can occur as a major manifestation of neuroblastoma.

Hepatic pulmonary fusion in neonates

OBJECTIVE

This report discusses the relationship of supradiaphragmatic hepatic tissue that is fused to the lung (through a diaphragmatic defect) with pulmonary hypoplasia-a new constellation of findings.

CONCLUSION

Hepatic pulmonary fusion should be suspected in instances of apparent diaphragmatic hernia characterized by mediastinal shift towards the hypoplastic lung or when the mediastinum does not shift away from the mass.

Appropriate imaging in children with skull fractures and suspicion of abuse

PURPOSE

To define the role of computed tomography (CT) in children aged 2 years and younger with head trauma, suspected abuse, and normal neurologic findings.

MATERIALS AND METHODS

From 1992 through 1995, 87 consecutive children with skull fractures visible at plain radiography were referred to child protective services for evaluation of suspected abuse. Their cases were retrospectively reviewed.

RESULTS

Of 67 children with normal neurologic findings, 35 (52%) were not referred for CT. No patient in this group developed delayed findings requiring further evaluation. Of the 32 (48%) who underwent head CT, only six (19%) had evidence of acute intracranial injury, despite the presence of minimal depression and stellate, multiple, and diastatic fractures. Of 20 children with acute neurologic findings, 16 (80%) had positive CT scans, which led to neurosurgical intervention in nine (45%).

CONCLUSION

No child with normal neurologic findings had a clinically important abnormality depicted at CT. CT scans did not alter clinical management, clinical outcome, or legal outcome. Thus, routine CT of all patients with skull fractures in this population may be unnecessary.

Proton magnetic resonance spectroscopy in children with Sturge-Weber syndrome

Quantitative proton magnetic resonance spectroscopy was performed on six children with Sturge-Weber syndrome following gadolinium enhanced magnetic resonance imaging (MRI). MRI revealed only unilateral involvement in all cases. The mean concentration (mmol/kg wet weight) of the neuronal marker N-acetyl-aspartate was significantly reduced by 37% in the ipsilateral gadolinium enhanced volume of interest compared to a similarly placed contralateral volume of interest (5.39 +/- 1.70 [SD] vs 8.50 +/- 1.14, P < .005, two-tailed paired Student's t-test). Decreased N-acetyl-aspartate in the ipsilateral volume of interest was observed in all patients studied. No significant differences were found in the concentrations of creatine/phosphocreatine or choline compounds between the ipsilateral and contralateral volumes of interest. These findings give possible new insight into the pathophysiology of this disease and suggest that quantitative proton magnetic resonance spectroscopy may be useful for the early characterization and monitoring of neuronal dysfunction or loss in infants and children with Sturge-Weber syndrome.

Evaluation of contrast media for bronchography

BACKGROUND

Bronchography is occasionally needed for the evaluation and management of some congenital pulmonary anomalies as well as some acquired diseases, usually of the tracheo- bronchial tree. There is currently no effective, approved contrast agent for this imaging techniq ue.

OBJECTIVE

We evaluated five agents (barium sulfate, iohexol, propyliodone oily, propyliodone aqueous, and perflubron) in terms of image quality, histologic changes, and effects on hemodynamics, blood gases, and standard laboratory tests in New Zealand White rabbits.

MATERIALS AND METHODS

Animals were anesthetized and intubated. Each contrast agent (0.25 ml/kg) was administered intratracheally. Three animals in each group had intravenous lines placed for blood sampling and blood pressure monitoring and were sacrificed at 1 h. An additional three animals for each agent were sacrificed at 24 h and 1 week after imaging. Blood samples were taken immediately before contrast instillation and at 1 h postbronchography. Fluoroscopic images were recorded on standard VHS video tape and evaluated in blind fashion. Segments of lung tissue and bronchi were obtained for histologic examination.

RESULTS

Necrosis and/or inflammatory infiltrates were noted in 78 % of the bronchograms performed with propyliodone aqueous, 67 % with propyliodone oily, 55 % with perflubron, and 33 % with iohexol 120, 240 and 350. No histologic damage was observed with barium. The propyliodones gave the best-quality imaging results and the most histologic changes. Iohexol, in any concentration, gave the least acceptable images and a moderate number of histologic changes. Barium sulfate demonstrated acceptable images with virtually no histologic changes.

CONCLUSION

From the histologic and imaging results, barium is the best available contrast material for bronchography.