Neuroradiology of pediatric posterior fossa medulloblastoma.

Medulloblastoma of the cerebellum is a common intracranial neoplasm in children and presents many faces in medical imaging. Characteristic or classic features, such as increased attenuation on unenhanced CT, midline location and well defined margins, are commonly present in childhood cases of posterior foassa medulloblastoma, although atypical imaging features are being noted more frequently with the increased dependence on MR as the diagnostic modality of choice. Carefully performed CT and MR both initially provide suitable geography and characteristics, but MR is superior in the detection of pre- or post-operative neoplastic spread elsewhere in the subarachnoid space. Accurate establishment of disease extent is essential in planning both surgical resection and adjuvant therapy.

Neuroimaging of childhood craniopharyngioma.

The imaging of craniopharyngioma may include plain skull x-rays, computer tomography (CT) scans, magnetic resonance imaging (MRI) and angiography. Coronal studies are essential to properly define the regional anatomy. The solid or cystic character of the lesion is especially apparent with contrast enhancement. MRI adds a sagittal projection which is useful, and its increasing sophistication may eventually make angiography superfluous in these tumours. The appearance of craniopharyngiomas in each modality is described, including 3D, and an ideal imaging strategy presented. Postoperative imaging is best done with both MRI and CT, and enhanced studies done within 48 h to avoid the effect of surgical trauma.

Edward B. D. Neuhauser Lecture. Pediatric neuroradiology: its evolution as a subspecialty.

Pediatric neuroradiology emerged as the first formal subspecialty of pediatric radiology during the late 1960s. The history of its development as an unusual and effective combination of an age-related and a specific organ-directed clinical subspecialty, and the considerable technical adaptation and innovation within the diagnostic imaging so required, merits its inclusion within the history of the modern matrix of radiology. This Neuhauser Lecture outlines the odyssey of this subspecialty until the present: the adaptation of techniques and equipment to accommodate imaging of patients of all sizes--from 1-kg infants to young adults--and the understanding of the wide spectrum of CNS diseases, many often extremely complex. The evolution of this special body of knowledge and experience, the established and productive fellowship programs, and the significant part pediatric neuroradiology now plays in major scientific and professional associations and societies have led to this subspecialty becoming a lifelong persuasion for a growing number of radiologists.

Radiology of the developing central nervous system.

Functional and anatomical imaging of the developing central nervous system continue to engender considerable interest. Structural anomalies have been further defined and catalogued, aiding in the diagnosis and genetic counseling of children with developmental delay. Anomalous development of the brain has recently been linked to certain neuropsychiatric disorders. The natural course of many of the metabolic brain disorders has now been chronicled with imaging studies, rendering standards on which to evaluate efficacy of treatment.

Primary meningeal tumors in children: correlation of clinical and CT findings with histologic type and prognosis.

PURPOSE: To identify the radiologic features that might help in preoperative differentiation of the meningiomas from the remaining primary meningeal tumors, in particular the malignant tumors. METHODS: The clinical and computed tomographic features of 21 children with histologically proved primary meningeal tumors were analyzed. FINDINGS: Benign tumors (meningiomas) are more likely to occur in older children, to have longer symptom duration, and to have CT appearances similar to the "typical" adult meningioma. Atypical CT features suggest a malignant meningeal tumor, such as meningeal sarcoma, melanoma, or meningeal primitive neuroectodermal tumor. The recent identification of a new subtype of meningioma (a "sclerosing" group) is discussed. This is common in children and the CT and clinical features are similar to those seen in other meningiomas. It is frequently mistaken histologically for an intraaxial tumor, or for an atypical or malignant meningioma. These sclerosing meningiomas may also show brain invasion but despite this, in the short term, the prognosis is no different from other meningiomas. CONCLUSION: The bad reputation previously ascribed to childhood primary meningeal tumors should be confined to that small group that are malignant. Meningiomas have a more favorable outlook.

Neuroimaging and pediatrics.

The emphasis in understanding significant categories of pediatric brain and spinal cord lesions, such as brain neoplasms, white matter diseases, fetal abnormalities and lesions of the pituitary gland, is changing towards a clinical perspective with respect to modern imaging techniques. The initial experience with magnetic resonance imaging (MRI), Doppler sonography, computerized tomography (CT), and high-resolution ultrasound (US) is now being consolidated, compared and contrasted with each other and with the increasing clinical experience, particularly in diseases that are peculiar to childhood.

Melanotic neuroectodermal tumor of infancy: clinical, radiologic, and pathologic findings in five cases.

Five pathologically proved melanotic neuroectodermal tumors of infancy are reported. These rare neoplasms of infancy exhibit a distinct predilection for the maxillary bone. Three tumors originated in the maxilla, one in the calvaria, and one in the cerebellar vermis. Those occurring in bone did not metastasize but were locally invasive, as reflected in their radiologic appearance. Bone erosion, expansion, hyperostosis, and osteogenesis can occur in the same neoplasm and were appreciated best on CT. MR imaging showed the soft-tissue component and extent of the neoplasm better than CT did. The pathologic findings from all five cases (and one possibly related melanotic tumor of the face) revealed abundant melanin. MR imaging of two melanotic tumors showed isointense T1-weighted and slightly hyperintense T2-weighted signals. This appearance is contrary to that of most melanin-containing tumors, which exhibit enhanced T1 and T2 relaxation, and indicates that variables other than the absolute amount of melanin may determine the MR signal. Clinically, rapid neoplastic growth and excessive melanin production by the tumor cells caused facial disfigurement and visible blue black discoloration. All five melanotic neuroectodermal tumors were resected and the vermian tumor was also irradiated. Four of five children were well and free from disease 1 month to 7 years after resection. The calvarial tumor was incompletely resected and involved the underlying brain, eventually causing death. The clinical, radiologic, and pathologic features of melanotic neuroectodermal tumors of infancy are reviewed. Melanotic neuroectodermal tumors of infancy that involve bone can be diagnosed from the clinical and radiologic findings. Prompt diagnosis and surgical resection are essential for cure.

Benign intrinsic tectal "tumors" in children.

A specific group of intrinsic dorsal midbrain tumors was identified in six children by computerized tomography (CT) and magnetic resonance (MR) imaging. Each patient presented with raised intracranial pressure as a result of hydrocephalus due to obstruction of the sylvian aqueduct. No patient had brain-stem signs referable to the tectal tumor initially or subsequently. All six children underwent cerebrospinal fluid (CSF) diversionary procedures. The radiological features were consistent and specific, with all patients showing tectal calcification or primary increased attenuation of the tectal plate on CT scans. In addition, lack of contrast enhancement was noted initially in four patients and eventually in all six patients. In all patients MR imaging showed a focal tectal tumor distorting the collicular plate with no cystic component and increased signal intensity on T2-weighted images. There has been no evidence of progression in these six patients in the follow-up period ranging from 8 months to 17 years (8 months and 2 1/2, 4 1/2, 8, and 17 years). Diversion of CSF has been the only surgical treatment and no patient underwent deep x-ray therapy. Five patients have had normal intellectual development. In contrast to the majority of previously described periaqueductal and tectal tumors, this group of lesions appeared to be truly benign. The authors suggest that patients presenting with these clinical and radiological features may be managed by CSF diversion, serial examination, and MR imaging.

Primary neoplasms of the central nervous system in children.

Modern diagnostic imaging techniques are able to detect primary neoplasms of the central nervous system (CNS) in children safely and accurately but with less specificity as to cell type or degree of malignancy. These neoplasms, often peculiar in cell type and size, mediated by hydrocephalus in their clinical presentation, demand careful and often extensive imaging techniques best to evaluate their geography and character. Added to these basic observations, determination of the neoplasm from surrounding edema, detection of possible spread, and evaluation of residual or recurrent neoplasm are prime responsibilities of the pediatric neuroradiologist toward the child, neurosurgeon, and oncologist.

Diastematomyelia in 172 children: the impact of modern neuroradiology.

The increasing sophistication of neuroradiology has significantly and progressively improved the diagnosis of diastematomyelia in 172 children presenting at the Hospital for Sick Children, Toronto, over a 40-year period. Standard radiography, computed tomography and magnetic resonance imaging are all necessary to accurately assess all the facets of this most interesting of spinal cord anomalies.

Computed tomography in intracranial, supratentorial metastases in children.

This study compares the CT characteristics in a consecutive sample of supratentorial metastases (n = 31) with primary tumors of the same location (n = 49) in childhood. Postcontrast CT was performed in all but one of the metastases cases. In all but one of these children the location and type of primary tumor was known at time of occurrence of cerebral metastasis. Primary CNS tumors (n = 12) had a higher incidense of supratentorial metastatic spread than tumor originating elsewhere. Three children had diffuse subarachnoid seeding, while 28 had solid tumors (21 solitary, 7 multiple). The predilection location for the solid metastases was the gray-white matter junction (n = 12). The following CT findings were significantly less frequent in metastases than in primary tumors (P less than 0.05): Midline location, calcification and cyst formation. On the other hand bleeding, pronounced contrast enhancement and location in the gray-white matter junction were more frequent in the metastatic group (P less than 0.05).

Evaluation of the infant spine by direct sagittal computed tomography.

Direct sagittal computed tomography (CT) and metrizamide myelography, in addition to standard axial CT, have proven most useful in evaluation of complex anomalies of the infant spine. Direct sagittal CT was performed by placing the entire infant sideways and supine within the gantry after metrizamide was injected. This technique was performed in six infants with diagnoses of lipoma with dysraphism, lipomyelomeningocele, lipomyelocystocele, lumbosacral agenesis with cord regression, capillary hemangioma, and vertebral osteomyelitis. The technique showed the relation and/or extension of lesions in the dorsal ventral plane, particularly the presence or absence of subarachnoid, enteric, or genitourinary communication. Spinal and paraspinal anatomic detail was also demonstrated beautifully.