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Biomedical subjects

G Di Chiro

Publications and source records attributed to G Di Chiro.

At least 109 records · Page 6Linked to original sources
PubMed1983

Alzheimer's disease: focal cortical changes shown by positron emission tomography.

Local rates of cortical glucose metabolism were estimated by positron emission tomography in 13 right-handed patients with Alzheimer's disease. Individuals with disproportionate failure of language function had markedly diminished metabolism in the left frontal, temporal, and parietal regions. Patients with predominant visuo-constructive dysfunction evidenced a hypometabolic focus in the right parietal cortex. Patients with memory failure as the most apparent feature had no significant metabolic asymmetry in cortical regions. In all subjects, verbal competency generally correlated with metabolic activity in the left frontal and temporal areas, while visuo-constructive test performance was linked to glucose utilization in the right parietal lobe.

Aged↗
PubMed1983

Successful treatment of a group of spinal cord arteriovenous malformations by interruption of dural fistula.

As demonstrated by selective spinal cord arteriography, over 80% of spinal cord arteriovenous malformations (AVM's) occupy a predominantly extramedullary position. Current therapy frequently requires surgical stripping of the long dorsal intradural vessel(s) from the underlying spinal cord over many cord segments. The authors report six patients with a dural arteriovenous fistula fed by a cluster of abnormal epidural arteries. These vessels, which surrounded and were embedded into the dural covering of a thoracic nerve root, drained into a long sinuous intrathecal paramedullary vein(s). The angiographic and surgical appearance of the intradural component of these lesions was identical to that of lesions previously classified as Type I AVM's of the spinal cord. All patients had symptoms and signs of myelopathy. In five patients, surgery was limited to coagulation and excision of the extradural vessels and division of the intradural arterialized vein. Progressive improvement began within days following surgery. No residual abnormality was demonstrated by postoperative selective spinal cord arteriography, which was performed in all five patients. The findings support those of Kendall and Logue, that surgery restricted to elimination of the arteriovenous fistula at the intervertebral foramen is curative, and that more extensive surgery is unnecessary for this subgroup of AVM's of the spinal cord. These lesions comprise a sizable percent of all spinal AVM's. Resolution of myelopathy in these patients supports the hypothesis that venous hypertension causes chronic progressive myelopathy.

Adult↗
PubMed1982

Digital subtraction angiography and dynamic computed tomography in the evaluation of arteriovenous malformations and hemangioblastomas of the spinal cord.

Digital subtraction angiography (DSA) and dynamic computed tomography (DCT) were used in the evaluation of five patients with surgically approachable vascular lesions of the spinal cord, including three arteriovenous malformations (AVM), one hemangioblastoma, and one lesion with a questionable radiographic-surgical diagnosis (AVM? hemangioblastoma?). Digital subtraction angiography was positive in three of the five cases and was particularly informative in the patient with hemangioblastoma, even vis a vis arteriography, which is considered the definitive diagnostic test for these lesions. Dynamic computed tomography was positive in four of the five cases. From this preliminary study, DSA and DCT appear to be useful screening and follow-up procedures which, in a number of aspects, complement each other.

Angiography↗
PubMed1982

Work in progress: [18F] fluorodeoxyglucose and positron emission tomography in the evaluation of radiation necrosis of the brain.

Five patients who had undergone radiation therapy for cerebral tumors and whose conditions were deteriorating were examined by means of positron emission tomography (PET) with [18F] fluorodeoxyglucose. All five cases had similar clinical and computed tomographic findings. Using the PET technique the two cases of radiation necrosis were distinguished from the three recurrent tumors. In the two cases of radiation necrosis the rate of glucose utilization in the lesion was markedly reduced compared with the normal brain parenchyma. In the recurrent gliomas, however, the glucose metabolic rate was elevated. All five diagnoses were confirmed by biopsy or autopsy.

Astrocytoma↗
PubMed1982

Glucose utilization of cerebral gliomas measured by [18F] fluorodeoxyglucose and positron emission tomography.

Positron emission tomography was used to measure local cerebral glucose utilization by the 1-[18F]fluoro-2-deoxy-D-glucose technique in 23 patients with cerebral gliomas. All 10 high-grade (III and IV) astrocytomas demonstrated a region of high activity with a glucose consumption of 7.4 +/- 3.5 (SD) mg/100 gm per minute. The 13 low-grade (I and II) gliomas had a glucose metabolic rate of 4.0 +/- 1.8 mg/100 gm per minute, with no distinctly visible hot spot. Thus, we found a correlation between rate of glycolysis and malignancy in primary cerebral tumors. Cerebral cortical glucose utilization was often depressed in areas adjacent to or neurally connected to the tumor site, and there was focal irregular delta wave EEG activity in these areas.

Adult↗
PubMed1981

Primary demyelinating disease simulating glioma of the corpus callosum: report of three cases.

Computerized tomography (CT) has made it easier to distinguish tumoral from nontumoral diseases of the central nervous system. In the presence of mass effect, however, this distinction may be difficult or impossible to make. Primary demyelinating disease may occasionally present as a focal cerebral mass. The authors report three cases of primary demyelinating disease of the brain involving the corpus callosum and periventricular white matter and associated with mass effect, which proved difficult to differentiate from infiltrating "butterfly" gliomas.

Adult↗
PubMed1980

Surgically correctable lesions solely detected by CT scan in adult-onset chronic epilepsy.

A prospective study of 162 patients with adult-onset chronic epilepsy revealed 4 in whom computed tomographic scanning was the only diagnostic test that detected the presence of a surgically correctable cerebral lesion. These patients had suffered from seizures for 1 to 14 years and at the time of operation demonstrated no clinical neurological deficits except organic mental changes.

Adult↗
PubMed1980

Design of a high resolution positron emission tomograph: the Neuro-PET.

The design of a high resolution positron emission tomograph is described. The scanner has four rings of detectors with an inside diameter of 38 cm and produces seven simultaneous slices, including three cross-slices. Each ring contains 128 bismuth germanate scintillation detectors with dimensions of 8.25 x 20 x 35 mm; adjacent crystals are separated by tapered tungsten septa that extend to within 7.5 mm of the front faces. The anticipated geometrical spatial resolution of the scanner is 4.5 mm full width at half maximum (FWHM) at the center of the image, and the sensitivity is 44,000 true counts/sec/ring (390,000 counts/sec total) for a uniform phantom 20 cm in diameter containing 1 muCi/cc activity. There are interchangeable collimators for use in high count rate studies, for narrowing the slice width from 1 cm FWHM to 5 mm FWHM, and for ultra-high resolution studies with a 2.5 mm FWHM geometrical point spread function. The electronic circuitry has separate timing and energy verification channels and can detect 95% of the coincidences with a timing window (twice the maximum time between two coincident pulses) of 14 nsec. The count rate capability of the electronics is 150,000 counts/sec/ring and 1.5 million counts/sec total.

Bismuth↗
PubMed1980

Experimental glioma in primates: a computed tomography model.

Owl and squirrel monkeys inoculated intracerebrally with human polyomavirus obtained from the brain of patient with progressive multifocal leukoencephalopathy developed cerebral gliomas. Among these tumors, three out of five were detected and accurately localized by contrast enhanced computed tomography (CT) when the animals were still clinically normal. Various CT features of these tumors corresponded to specific pathologic changes, such as histologic type and presence of hemorrhage and necrosis. Also, tumor progression was clearly demonstrated in repeat scans of one animal. The CT sensitivity and the capability of distinguishing various pathologic features are encouraging. It appears that a much needed, suitable model of experimental cerebral tumors in primates is now available for CT studies.

Animals↗
PubMed1980

Explanation of cerebral white--gray contrast in computed tomography.

The difference in Hounsfield number between white and gray brain tissue is calculated from published chemical compositions and density values. The result of 5.5 Hounsfield units at typical CT energies is in excellent agreement with experiments. The difference arises because gray matter contains 8% more oxygen and 8% less carbon, due to its higher water and lower lipid content, and this increases the photoelectric absorption. Efforts to obtain greater contrast by lowering the X-ray energy will be offset by the noise increase at low energies.

Animals↗
PubMed1980

Cerebral mass lesions in torulosis demonstrated by computed tomography.

Cryptococcus neoformans is an ubiquitous yeast. As a budding type of fungus, it is also known as Torula histolytica and is a common cause of infection of the central nervous system (CNS), particularly in debilitated and immunodeficient patients. We have examined 12 patients with computed tomography who had well documented cryptococcal CNS infection and will review our findings in this paper. Three of these patients had mass lesions, while nine others had a variety of changes such as ventricular dilatation, cortical atrophy, and focal ischemic changes.

Adolescent↗
PubMed1980

Serial measurements of CT attenuation and specific gravity in experimental cerebral edema.

Vasogenic cerebral edema was induced cryogenically in rhesus monkeys. Serial scans in both axial and coronal planes were used to study the onset, peak, and regression of edema. Progression of edema, predominantly involving the white matter, was analyzed from the postmortem distribution of a blood/brain barrier indicator (Evans blue) injected at surgery. Specific gravity was measured in fresh, unfixed specimens from both the edematous and normal hemispheres and correlated with corresponding CT attenuation values obtained before death. The drop in specific gravity closely corresponded to the decrease in CT attenuation.

Animals↗
PubMed1980

A new CT pattern in adrenoleukodystrophy.

A new CT pattern was observed in 2 patients with adrenoleukodystrophy (ALD). This pattern, which the authors call Type II, is characterized by the absence of posterior periventricular areas of decreased attenuation around the trigone on non-contrast scans: after contrast infusion, however, there is striking enhancement of various white-matter structures (tracts or fiber systems) such as the internal capsules, corpus callosum, corona radiata, forceps major, and cerebral peduncles. This is different from numerous previous descriptions of the CT pattern in ALD. Type II ALD does not appear to have been seen in any other leukoencephalopathy and is probably specific for a phenotypic variant or an evolving stage of ALD.

Child↗
PubMed1980

Mapping of cerebral cortical strokes in Rhesus monkeys by laser Doppler spectroscopy.

We have demonstrated the feasibility of using laser doppler spectroscopy to map regional blood flow distribution on the surface of the cerebral cortex. Rhesus monkeys underwent craniotomy, with replacement of part of the calvarium by a transparent plastic dome. A stroke was produced on one side by ligation of the middle cerebral artery. A flow index was computed from a weighted bandwidth of the doppler spectrum of helium-neon laser light scattered from the surface of the cortex, the doppler shift being due to scattering from moving blood cells in the microcirculation. By measuring the doppler flow index at a grid of points over the surface, the region of the stroke was easily delineated, and its progression with time observed. The method provides a rapid measurement with a spatial resolution of about 1 mm.

Animals↗