Comparison of MRI and MRA findings in children with a variety of neurologic conditions.

The role of MRA in the evaluation of children is evolving. We compared MRA and MRI in children with a variety of neurologic conditions to determine when MRA provides positive, cost-beneficial information. A total of 114 patients were retrospectively studied. MRA and MRI were performed and compared. MRA was abnormal in 34 (30%) of 114 patients: five (83%) of six with Menkes' disease, four (33%) of 12 with sickle cell disease, 12 (38%) of 32 with vascular malformations, one (6%) of 17 with headaches, seven (24%) of 24 with new focal deficits, one (10%) of 10 with seizures, and four (31%) of 13 with miscellaneous diagnoses. MRA and MRI were concordant in 73 (64%) of 114. Maximum concordance was in patients with Menkes' disease (100%) and minimum in those with new focal deficits (50%). The best MRA cost/benefit ratios were obtained in patients with Menkes' disease, vascular malformations, and sickle cell disease. A normal MRI usually forecasted a normal MRA. However, abnormal MRI findings did not always predict MRA abnormalities. Positive, cost-beneficial information is provided by MRA mostly in conditions known to involve the cerebral vasculature. Indications to perform MRA should be based on the neurologic diagnosis and MRI findings.

MRI appearances of metachromatic leukodystrophy.

BACKGROUND: The leukodystrophies constitute a wide spectrum of cerebral disorders of varying etiology. The imaging appearances on CT and MRI are recognizable as abnormalities of white matter; however, it may be impossible to arrive at the correct diagnosis based on imaging studies alone. PATIENTS AND METHODS: Three patients of varying age and clinical symptomatology diagnosed with metachromatic leukodystrophy (MLD) had remarkably similar MRI appearances. A "tigroid" or "leopard-skin" appearance was demonstrated within deep white matter in each case. RESULTS: All of the patients had biochemical confirmation of MLD. CONCLUSION: Although the "tigroid" pattern previously was considered to be pathognomonic of Pelizaeus-Merzbacher disease, the diagnosis of MLD must now be considered when these MRI appearances are encountered.

Abnormal diffusion-weighted MRI in medulloblastoma: does it reflect small cell histology?

A 12-year-old boy presented with the classic CT and MRI findings of medulloblastoma and the unusual finding of increased signal on diffusion MRI. The small-cell histology of medulloblastoma may account for the increased signal seen on diffusion MRI. Diffusion MRI with echoplanar technique may be useful in evaluation of these tumors and metastatic disease.

Respiratory foreign bodies and Eikenella corrodens brain abscess in two children.

We report the coexistence of aspirated foreign bodies and brain abscess in two boys. One child had aspirated a metallic needle, and in the other boy partially embedded sunflower seeds were found in the bronchial wall. Both patients had growth of Eikenella corrodens (oral gram-negative flora) from the abscess. Aspirated foreign body in the respiratory tract should be one of the diagnostic considerations if any of the normal oropharyngeal organisms such as E. corrodens is the causative organism of brain abscess.

Head trauma: CT scan interpretation by radiology residents versus staff radiologists.

PURPOSE: To determine the rate and clinical outcome of discrepancies in interpretation by radiology residents and staff neuroradiologists of posttraumatic cranial computed tomographic (CT) scans. MATERIALS AND METHODS: Prospective evaluation was performed for 419 consecutive emergency posttraumatic cranial CT studies that had been interpreted by radiology residents on call over a 16-month period. Discrepancies between the interpretations made by residents and those made by staff radiologists were divided into two groups: failure to recognize an abnormality (false-negative finding) and interpretation of normal as abnormal (false-positive finding). Discrepancies were considered major if they could affect patient care in the emergency setting and minor if they could not. RESULTS: Major and minor discrepancies were 1.7% and 2.6%, respectively, among interpretations made by residents and those by staff radiologists. Major discrepancies were four subdural hematomas, one pneumocephalus, one hemorrhagic contusion, and one subarachnoid hemorrhage. Minor discrepancies included six skull and five facial fractures. The discrepancy rate was statistically significantly higher (12.2%) when CT findings were abnormal than when they were normal (1.5%). No change in treatment was attributed to the delay in diagnosis. CONCLUSION: A low discrepancy rate was found between interpretations made by radiology residents and those made by staff neuroradiologists of posttraumatic cranial CT scans. There were no adverse clinical outcomes.

Rasmussen encephalitis: complementary role of multitechnique neuroimaging.

Rasmussen encephalitis is a chronic, progressive inflammation of the brain of unknown origin. Early diagnosis and treatment with immunoactive agents and/or hemispherectomy are sought to prevent the progressive cognitive decline that accompanies this disease. Combined anatomic and functional neuroimaging may serve to focus the diagnostic workup and to hasten brain biopsy for definitive diagnosis. Two biopsy proved cases of Rasmussen encephalitis are presented. The importance of MR imaging, single-photon emission computed tomography, and proton MR spectroscopy in the workup of this disease is discussed.

Central nervous system tumors of childhood.

Primary tumors of the central nervous system are the most common solid tumors of childhood. Although numerous tumors of the brain and spine are common to both pediatric and adult population groups, there are many tumors unique to infancy and childhood. This article describes the characteristic locations, clinical presentations, and imaging features of these tumors.

A newly recognized cause of wheezing: AIDS-related bronchial leiomyomas.

We present two human immunodeficiency virus-infected children who developed wheezing and radiological evidence of pulmonary air trapping due to intra- and peribronchial leiomyomas. At autopsy, leiomyomas were also found in their spleens, which to our knowledge, has never been reported. The smooth muscle tumors were strongly positive for the Epstein-Barr virus, as demonstrated by in situ hybridization to Epstein-Barr virus-encoded ribonucleic acid, confirming the findings of recent investigators and linking these tumors to the Epstein-Barr virus.

Coarctation of the aorta: diagnostic imaging after corrective surgery.

The clinical evaluation and management of the patient with coarctation of the aorta continues to evolve. Traditional imaging evaluation by plain film chest radiography, barium esophagography, and arteriography with pressure measurements across the coarctation has been largely supplanted by Doppler echocardiography and magnetic resonance imaging (MRI). The complications of surgery and balloon angioplasty, including residual or recurrent coarctation and aneurysm, can also be evaluated noninvasively by echocardiography and MRI. Chest radiography continues to play an important role in "first discovery" imaging in asymptomatic patients.

Tetralogy of Fallot: diagnostic imaging after palliative and corrective surgery.

Tetralogy of Fallot was invariably fatal until the development of palliative and later corrective surgical procedures. The prognosis for children with tetralogy of Fallot continues to improve almost a half century after the earliest palliative surgical procedure was performed successfully. Imaging of the child and adult after surgery for tetralogy of Fallot remains an important challenge because surgical complications or limitations frequently require imaging for complete evaluation and further management of the patient. Traditional imaging by chest radiography and arteriography has been largely replaced by echocardiography and ultrafast and conventional CT, as well as magnetic resonance imaging. This article reviews those aspects of diagnostic imaging that are appropriate to study the postoperative chest in the child or adult with tetralogy of Fallot.

Sedation of difficult-to-sedate children undergoing MR imaging: value of thioridazine as an adjunct to chloral hydrate.

OBJECTIVE: The purpose of this prospective study was to evaluate the safety and efficacy of thioridazine as an adjunct to chloral hydrate sedation when children undergoing MR imaging are difficult to sedate. SUBJECTS AND METHODS: All 87 children in the study either could not be sedated with chloral hydrate alone or were mentally retarded. Thioridazine (2-4 mg/kg) was administered orally 2 hr before and chloral hydrate (50-100 mg/kg) was administered orally 30 min before the 104 MR examinations. All children were monitored by continuous pulse oximetry. All images were individually evaluated by pediatric radiologists and were graded acceptable if they contained only minimal motion artifact or no motion artifact. Studies were considered successful only when 95% or more of the images were acceptable. RESULTS: MR imaging was successful in 93 (89%) of 104 examinations. The success rate for children entered into the study because of prior failure of chloral hydrate sedation was not significantly different from the success rate for children with mental retardation. A tendency for increasing failure rate with age was not significant. No serious complications occurred during the study. The most common adverse reaction, transient reduced oxygen saturation, was seen in five children. Other adverse effects encountered were vomiting in four children, hyperactivity in two children, transient tachycardia in one child, and prolonged sedation in one child. No child required hospitalization because of an adverse reaction to sedation. CONCLUSION: The study indicates that thioridazine is a safe and effective adjunct to chloral hydrate when a child undergoing MR imaging is difficult to sedate.

Undifferentiated (embryonal) sarcoma arising in conjunction with mesenchymal hamartoma of the liver.

The histogenesis of the undifferentiated (embryonal) sarcoma of the liver has been much debated. Originally, some investigators suggested that the tumor could originate from a mesenchymal hamartoma. Others doubted this hypothesis. The demonstration of alpha-1-antitrypsin in some tumors and of cytokeratins in others gave rise to new theories suggesting that the tumor was either a fibrous histiocytoma or a sarcomatoid hepatocellular carcinoma. As a new development in this search for the genesis of the undifferentiated (embryonal) sarcoma of the liver, this report describes a case that seems to substantiate, for the first time, the original hypothesis histogenetically linking the undifferentiated (embryonal) sarcoma and the mesenchymal hamartoma. The case is that of a 12-yr-old girl who developed an undifferentiated (embryonal) sarcoma of the liver in conjunction with a mesenchymal hamartoma. Furthermore, in places, the tumor exhibited striking epithelial differentiation as well as immunoreactivity for cytokeratins, alpha-1-antitrypsin and vimentin. Immunoreactivity for alpha-fetoprotein was limited to the areas of epithelial differentiation.

Cerebral syrinx with Chiari I malformation.

A 13-year-old female presented with acute left gaze paralysis. MRI revealed hydrosyringomyelia (HSM) with syringobulbia in the left pons extending cephalad into the centrum semiovale. A suboccipital craniotomy was performed and the foramen of Magendie was imperforate. Ocular movements normalized in 2 months and postoperative MRI confirmed resolution of the cerebral syrinx and syringobulbia and diminished HSM. This case represents an extreme example of the altered spinal fluid dynamics with Chiari I malformation. Theories on HSM are reviewed.

High-dose chloral hydrate sedation for children undergoing MR imaging: safety and efficacy in relation to age.

OBJECTIVE: Sedation is frequently essential for successful MR imaging, and chloral hydrate is the most commonly used drug for this purpose in infants and children. Our experience with these patients suggested that this sedative is less effective in older children, even when administered in high doses. However, no prospective study comparing the efficacy of chloral hydrate sedation for children of different ages undergoing MR imaging has been reported. Accordingly, we performed a study to evaluate the effectiveness and safety of chloral hydrate sedation in children of various ages. SUBJECTS AND METHODS: The study included 300 infants and children, 1 month to 11 years old (mean, 3 years), who were given oral chloral hydrate, 100 mg/kg, for sedation before MR imaging. The maximum total dose administered was 2.5 g, which limited the study to children who weighed 25 kg or less. Sedation was considered successful when MR studies were completed and at least 95% of the images had little or no motion artifact. RESULTS: Sedation was successful in 273 (91%) of 300 children. It was unsuccessful in nine of the 203 children who were 48 months old or younger (96% success rate) and in 18 of the 97 children who were more than 48 months old (81% success rate). A single-tailed t-test showed that the children in whom sedation was unsuccessful were significantly older than those in whom it was successful to the .0005 level of significance. The failure rate increased steadily for children more than 48 months old. Several failures may also have resulted from lengthy examination times. Adverse reactions to chloral hydrate sedation included hyperactivity (6%), vomiting (4%), and mild respiratory depression (4%). No adverse reaction was severe enough to require hospitalization. CONCLUSION: The higher failure rate for chloral hydrate sedation in children more than 48 months old suggests that the patient's age is an important limitation to the usefulness of chloral hydrate sedation for children undergoing MR imaging. However, the low rate of adverse reactions makes chloral hydrate a safe drug for sedation of children undergoing MR imaging.

Technetium 99mTc-HMPAO SPECT in children and adolescents with neurologic disorders.

We evaluated regional cerebral blood flow with technetium 99mTc hexamethylpropyleneamineoxime single photon emission computed tomography (SPECT) in 20 children and adolescents with neurologic dysfunction of varied etiology and abnormal electroencephalograms (EEGs). All patients were also examined with computed tomography (CT) and magnetic resonance imaging (MRI). Abnormal perfusion was found in 17 (85%) of 20 SPECT scans. Abnormal CT or MRI scans were noted in nine (45%) and in 10 (50%) of 20 cases, respectively. In eight (73%) of 11 cases with normal CT scans and in seven (70%) of 10 with normal MRI scans, the SPECT scan was abnormal. Abnormal regional cerebral blood flow on SPECT scans correlated better with EEG abnormalities than with neurologic examination or CT or MRI scan findings. We conclude that in children and adolescents with a spectrum of neurologic diseases and abnormal EEGs, abnormalities of brain structure or function are more likely to be documented by SPECT than by CT or MRI scans. SPECT findings correlate well with the location and type of EEG abnormality.

Benign hemorrhagic adrenocortical macrocysts in Beckwith-Wiedemann syndrome.

A new pseudotumorous lesion found in the adrenal cortex of six infants with Beckwith-Wiedemann syndrome is described. These cystic masses were discovered either prenatally by using sonography or early in the neonatal period as palpable flank masses. Imaging studies, including sonography and CT, could not confidently exclude malignancy. After the masses were removed surgically, histologic examination showed them all to be benign hemorrhagic macrocysts within the capsule or permanent cortex (in contrast to neonatal adrenal hemorrhage, which usually occurs more centrally in the fetal cortex). The cysts were as large as 8 cm in diameter, and in one case a solitary cyst was predominant. Hemihypertrophy was present in all cases. Four of the six lesions were right-sided, and there was a male-female ratio of 5:1. Benign hemorrhagic adrenocortical macrocysts are a cause of abdominal mass in the fetus and neonate with Beckwith-Wiedemann syndrome.

High dose chloral hydrate sedation for children undergoing CT.

Chloral hydrate is commonly used to sedate children before CT. However, no prospective study has been published of the safety and efficacy of chloral hydrate at high dose levels for children undergoing CT. We define high dose levels of oral chloral hydrate to be 80-100 mg/kg, with a maximum total dose of 2 g. High dose chloral hydrate sedation was administered orally to 295 children for 326 CT examinations. Adverse reactions occurred in 7% of the children, with vomiting being the most common (4.3% of children). Hyperactivity and respiratory symptoms each occurred in less than 2% of children. Prolonged sedation ( greater than 2 h) was not encountered in our series. Sedation was successful in producing motion free CT examinations, so that in 303 (93%) of the cases, no repeat CT scans were needed. We conclude that high dose oral chloral hydrate provides safe and effective sedation for children undergoing CT.