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Biomedical subjects

R A Zimmerman

Publications and source records attributed to R A Zimmerman.

At least 19 recordsLinked to original sources
PubMed1992

Vascular malformation with radiation vasculopathy after treatment of chiasmatic/hypothalamic glioma.

Chiasmatic/hypothalamic gliomas usually are histologically benign astrocytomas that may recur many years after diagnosis and treatment. Three children with chiasmatic/hypothalamic gliomas who were treated at the authors' institution returned 9.5, 11.5, and 2 years, respectively, after radiation therapy (RT) because visual and neurologic deterioration developed. Neuroradiographic studies, including arteriography in two of the patients, showed large mass lesions. These were presumed to be recurrence of tumor, and chemotherapy was administered. Pathologic examination of two children who died and of the third who had a biopsy revealed only a minimal amount of residual, histologically benign astrocytoma, whereas the bulk of the specimen consisted of numerous vessels of variable size. These probably represented incorporation of the rich vasculature in the chiasmal region into the tumor, which underwent degeneration secondary to RT. Radiographic methods did not distinguish progressive tumor growth from the vasculopathy and led to inappropriate clinical diagnoses and treatment.

Adolescent↗
PubMed1992

Choroid plexus carcinoma of childhood.

The presentation, growth patterns, and response to therapy of 11 consecutive children with choroid plexus carcinomas were analyzed, and the results were compared with the outcome reported in other series. Patients were a median of 26 months of age at diagnosis. Two patients had thalamic tumors, one had a posterior fossa primary, and the rest had ventricular lesions. Five of 11 (45%) children remain in continuous progression-free remission a median of 48 months from diagnosis. Four of the five in continuous remission had a "gross total" surgical resection, and only one received radiation therapy. Five of six patients with subtotal resections relapsed despite postoperative treatment with radiation therapy (three) and chemotherapy (one). The response to treatment with radiation therapy or chemotherapy at relapse was disappointing, with only one child (treated with etoposide) responding. In combination with other series, 11 of 14 children had prolonged progression-free survival after gross total resection (only two of whom received adjuvant therapy) compared with two of 20 after less than total resections, independent of the type of adjuvant therapy given. Adjuvant therapy for children with choroid plexus carcinomas is of unproven benefit, and this must be considered when analyzing innovative treatment trials for such children, especially for those with totally resected tumors. Patients with partially resected lesions fare poorly with present forms of treatment.

Child↗
PubMed1992

Hemifacial spasm: evaluation by magnetic resonance imaging and magnetic resonance tomographic angiography.

We evaluated 37 patients with hemifacial spasm and 16 age-matched control patients with other neurological disorders using magnetic resonance (MR) imaging, MR angiography, and MR tomographic angiography. MR tomographic angiography is a new technique using computer reconstruction of MR angiographic images to create coronal angiotomes that display tissue and arterial structures on the same image. Twenty-four of 37 (64.9%) patients with hemifacial spasm had ipsilateral vascular compression of cranial nerve VII or the pons noted by this technique, whereas only 1 of 16 (6.3%) control patients had compression. MR imaging and MR angiography were less sensitive and less specific in evaluating for vascular compression. This study supports vascular compression of cranial nerve VII or the pons as a cause of hemifacial spasm, and demonstrates MR tomographic angiography's value as an excellent, noninvasive technique to demonstrate the compression.

Adult↗
PubMed1992

Sensitivity of in vivo MRS of the N-delta proton in proximal histidine of deoxymyoglobin.

The sensitivity of in vivo MRS of the N-delta proton of the proximal histidine of deoxymyoglobin in human skeletal muscles is discussed. Longitudinal relaxation time T1 of this deoxymyoglobin signal was measured in cuffed human forearms at 1.5 T and found to be 9.9 ms. Deoxymyoglobin spectra can be obtained from a forearm in seconds. The detection sensitivity of deoxymyoglobin in fully ischemic skeletal muscles and that of 31P MRS of PCr in normal resting muscles are compared.

Adult↗
PubMed1992

Pediatric craniocervical spiral CT.

Spiral CT, which consists of rapid volumetric data acquisition and planar image display, was performed on 100 children undergoing examinations of the brain and head and neck for a variety of clinical indications. The technique was evaluated for image quality and impact on clinical practice. Images of the brain were generally of diagnostic quality in infants and young children but not in older children, due to their larger heads and present X-ray tube current limitations. The lower contrast resolution demands in imaging head and neck structures permitted acquisition of high quality images in all age groups. The rapidity of the technique allowed vascular phase imaging with one-sixth to one quarter the amount of contrast medium injected routinely, reduced the number of artifacts related to patient motion and occasionally permitted scanning of young patients without sedation. As a consequence, the spiral technique appears to have the potential for improving the efficiency and safety of diagnostic CT in investigation of the brain, head and neck in children.

Adolescent↗
PubMed1992

Investigation of stroke in sickle cell disease by 1H nuclear magnetic resonance spectroscopy.

Localized proton nuclear magnetic resonance spectroscopy (MRS), obtained with stimulated echo and spin echo sequences, MR imaging (MRI) and MR angiography (MRA) were used to study the brain in 13 children and adolescents with sickle cell disease. Regions of interest (ROI) studied by MRS included regions appearing normal on MRI as well as regions showing complications of sickle cell disease, including focal deep white matter areas of high signal intensity (deep white matter ischemia, DWMI) seen on long TR images, focal atrophic brain areas, and infarcts. The findings in these studies are summarized as follows: Normal-appearing regions on MRI have normal MRS. In ROI including small areas of DWMI, lactate elevation was not detected, but the levels of N-acetyl-aspartate (NAA) appeared slightly elevated. In areas of DWMI 1-2 cm in size, reduced blood flow could be seen on MRA and lactate elevation could be detected with MRS. When blood flow to a DWMI region was normal, NAA was reduced and there was little lactate elevation, as cell death had already occurred. ROI consisting of atrophic tissue had reduced NAA levels but total creatine levels were not changed. Sometimes lipids, presumably from broken cell membrane, could be detected. In regions of past massive stroke, all metabolites were absent except for small amounts of lactate or lipids.

Adolescent↗
PubMed1992

Desmoplastic primitive neuroectodermal tumor with divergent differentiation. Broadening the spectrum of desmoplastic infantile neuroepithelial tumors.

We report an unusual large, multicystic, posterior fossa neuroepithelial neoplasm involving the cerebellum, brain-stem, and quadrigeminal cistern of a 9-month-old girl. The neoplasm consisted of variably sized, sharply demarcated nests of small cells with a high nuclear-cytoplasmic ratio and moderately basophilic nuclei, embedded in a desmoplastic, immature-appearing, mesenchymal stroma. The nests contained mitoses but none were seen in the stroma. Glial fibrillary acidic protein (GFAP), neurofilament protein, synaptophysin, and cytokeratin (AE-1) were expressed in the nests. Mesenchymal cells were negative for neural markers but positive for vimentin and desmin. The neoplasm was interpreted as a mixed mesenchymal and primitive neuroectodermal tumor (PNET) with histologic features reminiscent of a recently described intraabdominal desmoplastic small cell tumor. The tumor responded poorly to chemotherapy and a second operation was performed 1 year later. The second specimen bore no resemblance to the original and consisted of epithelial-like nests and clusters of neoplastic cells frequently interrupted by sinusoidal vessels. Tumor cells had medium-sized vesicular nuclei with small nucleoli, and a granular cytoplasm. Occasional less cellular islands of neuropil-like tissue contained larger cells having eccentric, vesicular nuclei with prominent nucleoli and abundant pink cytoplasm. Mitoses were not conspicuous. Many cells expressed synaptophysin, neurofilament protein, and GFAP. Neurofilament protein was strongly positive in the larger, neuron-like cells and synaptophysin stained the neuropil-like areas strongly but was less prominent in the neuronal perikarya. Unexpectedly, the neuropil-like areas expressed epithelial membrane antigen, whereas the neuronal cells were negative for chromogranin A. The peculiar histologic picture, combination of phenotypic markers, and remarkable biologic behavior of this unusual tumor defies classification according to existing nomenclature and exemplifies the broad range of phenotypes expressed by primitive neuro-epithelial neoplasms.

Brain Neoplasms↗
PubMed1992

MR imaging of tuberous sclerosis: pathogenesis of this phakomatosis, use of gadopentetate dimeglumine, and literature review.

Findings on cranial magnetic resonance (MR) images were correlated with known histopathologic findings in 42 patients with tuberous sclerosis (TS), 17 of whom received gadopentetate dimeglumine, to extend the range of signs on MR images. Four neuroradiologists recorded the number, sites, configurations, and relative signal intensities of intracranial abnormalities. White matter lesions, found in 39 patients (93%), showed four distinct patterns: (a) straight or curvilinear bands extending radially from the ventricle through the cerebral mantle toward the cortex, (b) wedge-shaped lesions, (c) nonspecific conglomerate foci, and (d) cerebellar radial bands. It is concluded that cortical tubers, white matter lesions, subependymal nodules, and sub-ependymal giant cell astrocytomas (SGCAs) may be enhanced after administration of gadopenetetate dimeglumine. Enhancement of a TS lesion does not indicate neoplastic transformation into SGCA. Imaging surveillance every 12 months appears indicated during the peak ages (8-18 years) of occurrence of SGCA. The appearance of white matter lesions supports the theory that the cerebral lesions of TS may be caused by disordered migration of dysgenetic cells.

Adolescent↗
PubMed1992

Magnetic resonance imaging of pediatric posterior fossa tumors.

MR detected abnormality in all 115 pediatric patients who subsequently had pathologically proven posterior fossa tumors. In 114, the initial magnetic resonance (MR) diagnosis was that of brain tumor. In 1, with less than 1-cm2 area of gadolinium enhancement, the significance of the initial finding was uncertain. Common posterior fossa tumor subgroups (brainstem gliomas, cerebellar astrocytomas, primitive neuroectodermal tumors, and ependymomas) have relatively consistent presentations on imaging studies. However, less common tumors mimic the MR appearance of more common ones, while common tumors may also have atypical appearances.

Adolescent↗
PubMed1992

Abnormal magnetic resonance images in hemorrhagic shock and encephalopathy syndrome.

Hemorrhagic shock and encephalopathy syndrome is an acute childhood illness that involves the rapid onset of multisystem failure, including central nervous system, renal, cardiovascular, hepatic, and hematologic dysfunction, and often leads to death or serious neurologic damage. We report the first case of a child with hemorrhagic shock and encephalopathy in which magnetic resonance imaging was used to define the cortical hemorrhagic involvement.

Brain↗
PubMed1992

Proton magnetic resonance spectroscopy of pediatric brain tumors.

1H magnetic resonance spectroscopy allows the regional quantitation of a number of metabolites from the brain in a noninvasive fashion. Spectra were obtained from 5 normal children and 25 children with brain tumors. Choline (Cho), N-acetylaspartate (NAA), creatine and phosphocreatine, and lactate were quantitated in the form of ratios. The brains of normal children showed relatively high concentrations of Cho and NAA and virtually no lactate, as has been shown in adults. Benign astrocytomas and ependymomas were characterized by an elevation of the Cho:NAA ratio and an abnormal accumulation of lactate. Intrinsic malignant tumors were remarkable for an even higher Cho:NAA ratio but had no more lactate than was found in the benign tumors. Proton magnetic resonance spectroscopy may prove useful in characterizing neoplastic tissue in conjunction with more conventional imaging modalities.

Adolescent↗
PubMed1991

Update on technology diffusion.

Magnetic resonance imaging (MRI) continues to expand in influence as a diagnostic tool, with the number of units installed in the United States growing rapidly, according to an AHA technology assessment report. Technology assessment is being used more and more in decision making regarding the use of MRI and other diagnostic technologies. Two perspectives on the phenomenon are explored.

American Hospital Association↗
PubMed1991

Regional variation in brain lactate in Leigh syndrome by localized 1H magnetic resonance spectroscopy.

Localized water-suppressed 1H magnetic resonance spectroscopy was performed in an 11-month-old infant with Leigh syndrome. Spectra obtained from the basal ganglia, occipital cortex, and brainstem showed elevations in lactate, which were most pronounced in regions where abnormalities were seen with routine T2-weighted magnetic resonance imaging. This approach has allowed us to examine metabolism in brain tissue directly and noninvasively, and may provide a sensitive means for evaluating metabolic disease and the response to therapy in the brain.

Brain↗
PubMed1991

Use of computed tomography, magnetic resonance imaging, and localized 1H magnetic resonance spectroscopy in Canavan's disease: a case report.

The neuroradiological evaluation of Canavan's disease in a 38-month-old girl is discussed. Computed tomography showed diffuse symmetrical low attenuation values of the subcortical and deep cerebral white matter. Magnetic resonance imaging demonstrated symmetrical diffuse low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. With the use of 1H magnetic resonance spectroscopy, we were able to show elevated levels of N-acetylaspartic acid in the occipital lobe of our patient. The in vivo measurement of N-acetylaspartic acid in the brain by 1H magnetic resonance spectroscopy offers an additional noninvasive diagnostic test for establishing the diagnosis of Canavan's disease. With the increasing availability of magnetic resonance spectroscopy, clinicians may be able to confirm the diagnosis of Canavan's disease immediately after magnetic resonance imaging reveals the typical abnormalities of the white matter.

Amidohydrolases↗
PubMed1991

Late-onset globoid cell leukodystrophy mimicking an infiltrating glioma.

A 3 1/2 year old girl who developed a gradual left hemiparesis and hemianopia is reported. Neuroimaging studies demonstrated an infiltrating-like high density lesion which crossed the splenium of the corpus callosum, thought to represent a glioma. Subsequent brain biopsy established the correct diagnosis of globoid cell leukodystrophy (GCL), which suggests that the radiographic appearance of late-onset GCL may mimic that of an infiltrating glioma.

Brain↗
PubMed1991

Analysis of brain and cerebrospinal fluid volumes with MR imaging. Part I. Methods, reliability, and validation.

A computerized system was developed to process standard spin-echo magnetic resonance (MR) imaging data for estimation of brain parenchyma and cerebrospinal fluid (CSF) volumes. In phantom experiments, the estimated volumes corresponded closely to the true volumes (r = .998), with a mean error less than 1.0 cm3 (for phantom volumes ranging from 5 to 35 cm3), with excellent intra- and interobserver reliability. In a clinical validation study with actual brain images of 10 human subjects, the average coefficient of variation between observers for the measurement of absolute brain and CSF volumes was 1.2% and 6.4%, respectively. The intraclass correlations for three expert operators is greater than .99 in the measurement of brain and ventricular volumes and greater than .94 for total CSF volume. Therefore, the authors believe that their technique to analyze MR images of the brain performed with acceptable levels of accuracy and reliability and that it can be used to measure brain and CSF volumes for clinical research. This technique could be helpful in the correlation of neuroanatomic measurements to behavioral and physiologic parameters in neuropsychiatric disorders.

Algorithms↗