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Biomedical subjects

G Di Chiro

Publications and source records attributed to G Di Chiro.

At least 145 records · Page 8Linked to original sources
PubMed1977

Scleral calcifications in hyperparathyroidism: demonstration by computed tomography.

Scleral calcifications were demonstrated roentgenographically in two patients with known hyperparathyroidism and clinically normal eyes. In one of these patients, scleral calcification was evident both on plain films and with computed tomography (CT). In the second patient, a solitary plaque of calcified sclera was visible only by CT. Histopathologic examination of the eyes of a third hyperparathyroid patient who died during surgery demonstrated calcium plaques in the posterior sclera consistent with the CT appearance of the sclera in the other patients.

Adult↗
PubMed1977

Computed tomography of spinal cord arteriovenous malformations.

Computed tomography (CT) of the spine after intravenous contrast enhancement has been used in 4 patients with arteriovenous malformation (AVM) of the spinal cord. The enlarged, contrast-filled vessels constituting the malformation are visualized on CT scans. There was good correspondence between CT and selective angiography. CT may be a useful screening and follow-up method for AVM of the spinal cord and a safe procedure for assessing the results of therapy.

Angiography↗
PubMed1977

Delayed radiation necrosis of the brain.

The cases of six patients are presented to delineate the clinical profile of delayed radiation necrosis of the brain. In five the diagnosis was verified histologically. Symptoms most often begin 9 months to 2 years after radiotherapy. Progressive visual impairment and dementia are common following perisellar irradiation, while hemispheric signs predominate following irradiation of the cerebrum. Cerebrospinal fluid protein may be elevated. Focal delta slowing is usually present on electroencephalography. The necrotic brain may appear on radionuclide brain scan as an area of abnormal uptake and also act as an avascular space-occupying lesion. With computerized tomography, radiation necrosis appears as an intracerebral area with diminished absorption coefficient that is often enhanced with intravenous contrast medium. The syndrome may be sufficiently characteristic to eliminate the need for surgical exploration and biopsy in some cases. Cumulative experience suggests that the risk-to-benefit ratio of radiotherapy becomes increasingly unfavorable for most patients with benign intracranial neoplasms when the standard brain tumor dose of 5000 to 7000 rads is fractionated at greater than 200 rads per day.

Adenoma, Chromophobe↗
PubMed1977

Detection of orbital and intraocular foreign bodies by computerized tomography.

Localization of intraocular and orbital foreign bodies with computerized tomography (CT) was evaluated in eight patients and an experimental model. CT examination was particularly helpful in cases with multiple similar foreign bodies and in identifying foreign bodies too radiolucent to be seen by standard skull x-rays. Limitations of CT technique included insufficient resolution to localize a foreign body immediately adjacent to the sclera as either intraocular or extraocular, and obscuration of a small foreign body by artifacts from an adjacent, larger foreign body.

Adolescent↗
PubMed1977

Cerebral necrosis following irradiation and chemotherapy for metastatic choriocarcinoma.

A case of cerebral necrosis following radiation and chemotherapy in a patient with metastatic cerebral choriocarcinoma is reported. Computed tomography (EMI Scan) demonstrated evolution and enlargement of the necrotic lesion. This focus was surgically excised and histology is presented. The possible enhancement of radiation necrosis by chemotherapy is noted, but the continued need for simultaneous use of radiation and chemotherapy is recognized and discussed.

Adult↗
PubMed1977

Management of a patient with orbital varices, visual loss, and ipsilateral glaucoma.

A man with congenital orbital varices developed progressive ipsilateral visual loss beginning at age 62. Work-up demonstrated elevated intraocular pressure, decreased outflow facility, and mildly elevated episcleral venous pressure in the affected eye. Initiation of adequate glaucoma treatment was associated with interruption of declining visual acuity and with expansion of the constricted visual field. Medical control of coexisting glaucoma should be attempted prior to consideration of surgical intervention in any patient with visual loss and an ipsilateral orbital varix.

Epinephrine↗
PubMed1977

Slice geometry in computer assisted tomography.

In computer assisted tomography, the slice being imaged is not a uniform slab because (1) the X-rays are not parallel, (2) the source and detector may not have equal dimensions, (3) the source collimator may produce a penumbra region on the detector, and (4) in some machines two slices are scanned simultaneously from a common focal spot. One method of measuring slice thickness, uniformity, and overlap is with a phantom containing an aluminum strip at a 45 degree angle. This provides a direct display, in the viewing plane, of the slice profile. Measurements have been made on seven new tomographic scanners, and photographs and plots of slice geometry are presented. It is suggested that slice thickness be defined as the full width at half maximum sensitivity, but that this measure should not necessarily be used as the desirable increment between scans.

Humans↗
PubMed1976

An analysis of the first one thousand cerebral ACTA scans.

The first 1000 ACTA Scans of the brain are analyzed. ACTA Scanning is ideal for evaluating the ventricular system and other CSF containing spaces. High density lesions, such as intracerebral hematomas are depicted with great consistency. The method is less reliable for detecting subdural hematomas. For brain tumor screening, intravenously applied contrast agents are mandatory, so that tumors with subtle density changes can be identified more positively.

Brain Neoplasms↗
PubMed1976

Beam hardening in x-ray reconstructive tomography.

As a polychromatic X-ray beam passes through matter, low energy photons are preferentially absorbed, and the (logarithmic) attenuation is no longer a linear function of absorber thickness. This leads to various artifacts in reconstructive tomography. If a water bag is used, the nonlinear attenuation in bone causes a distortion of the bone values and a spill-over inside the skull, or 'pseudo-cortex' artifact. If no water bag is used, there is an additional effect due to the varying thickness of soft tissue which causes a depression of interior values, or 'cupping'. Both artifacts can be remedied by additional prefiltering of the beam and by applying a linearization correction to the detector outputs.

Diagnosis, Computer-Assisted↗
PubMed1976

Positional shift of intraventricular blood clots demonstrated by computed tomography.

Computed tomography with the patient in the prone position was employed to obtain information in a case of intraventricular hematoma secondary to arteriovenous maliformation. A gravitational shift in the position of the intraventricular blood clots was demonstrated by a scan obtained with the patient in the brow-down position. Consideration is given to the possible use of the "prone EMI scan" for other intracranial problems of differential diagnosis.

Adolescent↗
PubMed1976

Paraspinal muscle infarction. A painful complication of lumbar artery embolization associated with pathognomonic radiographic and laboratory findings.

Severe, prolonged back pain was observed in 2 patients following lumbar artery embolization with Gelfoam for angiomatous spinal lesions. Dense, persistent staining of the paravertebral muscles with a characteristic striated pattern and elevated levels of creatine phosphokinase suggested muscle infarction and necrosis. Similar angiographic and laboratory findings were reproduced in monkeys following arterial embolization with Gelfoam.

Adult↗
PubMed1976

Computed tomography of spinal cord after lumbar intrathecal introduction of metrizamide (computer-assisted myelography).

Computed tomography (CT) of the thoracic and cervical spine was carried out after lumbar intrathecal introduction of a water-soluble radiographic contrast medium (metrizamide). By choice, no head-down position of the patient was used to facilitate craniad movement of the contrast medium; rather, advantage was taken of the normal CSF flow. This technique, referred to as computer-assisted myelography (CAM), permits the demonstration of the metrizamide-containing subarachnoidal spaces surrounding the thoracic and cervical cord. Some examples of the diagnostic possibilities of the method are discussed.

Computers↗
PubMed1976

Technique for placement of experimental indwelling carotid artery catheter.

A technique for placement of an indwelling carotid artery catheter in the rhesus monkey is presented. These indwelling catheters have proved useful in the investigation of regional cerebral blood flow using xenon-133, positive contrast angiography, and fluorescein angiography. Although limited thus far to studies in experimental anemic stroke, this technique could be adapted to a variety of experimental situations in which serial evaluations of the cerebral vasculature are indicated.

Animals↗
PubMed1976

Diagnosis of radiosensitive hypothalamic tumors without craniotomy: endocrine and neuroradiologic studies of intracranial atypical teratomas.

Three patients with intracranial atypical teratomas presented with symptoms of endocrine dysfunction (diabetes insipidus, hyperprolactinemia, and anterior hypopituitarism) suggestive of a hypothalamic disorder. Computer-assisted tomography done in two of the three cases enabled us to document the presence of a mass and institute radiotherapy, without prior neurosurgical exploration. Computer-assisted tomography also provided a safe and effective method of assessing the effects of radiotherapy.

Adolescent↗
PubMed1975

Early clinical experience with the ACTA scanner.

An alternative method of computed tomography has been devised employing a new instrument, the ACTA scanner. This is a total-body scanner which permits study of virtually all body parts, since a water medium is not employed. Early clinical experience with this new method is discussed, and normal and pathological scans are presented.

Brain Diseases↗
PubMed1975

Theory of image reconstruction in computed tomography.

Mathematical methods are of central importance in the new technologies of radiographic and radioisotopic image reconstruction. The most important procedures are classified as Back-projection, iterative, and analytical (Two-dimensional Fourier, Filtered Back-projection). Back-projection played an important historical role but is no longer used because of sizable artifacts. Analytical methods excel in speed and accuracy when a large number of projections are available and are extensively used in x-ray imaging. Iterative reconstruction is more attractive when the number of views is limited, if noise is significant, and if additional factors, e.g., gamma-ray attenuation, are present. For these reasons, iterative methods are widely used in radioisotope imaging.

Computers↗