Biomedical subjects
Publications and source records attributed to J M Taveras.
Two cases of extradural epidermoid cyst and one case of xanthoma are reported in order to describe the computed tomographic and other radiographic findings. Contrast enhancement of the margin was seen in all of the cases. Absorption values almost as low as those found with cerebrospinal fluid were present in the central region of the lesions.
Primary intracranial intradural extraventricular epidermoid tumor may be suggested by the findings on computed tomography (CT), which is also useful during the follow-up period. Epidermoid tumors may exhibit minimal symptoms and have usually spread far beyond their original site by the time they are found. Early detection, delineation, and characterization are possible with CT.
Computer assisted axial tomography and the venous phase of carotid angiography provide complementary assessments of the ventricular and paraventricular structures. The computer assisted tomography more readily defines the ventricular system, but can prove weak in differentiating paraventricular gliomas, solitary metastasis and infarcts. Angiography plays a major role in differentiating between these three conditions, but is poor in accurately localizing and identifying intra- and paraventricular hemorrhage which is characteristically and expeditiously uncovered by C.T. scanning.
The retrospective evaluation of 100 cases of head trauma that were subjected to computerized tomography (CT) leads to the following conclusions: (1) Computerized tomography and plain skull survey, should be the first neuroradiological procedures to perform. (2) Angiography may be carried out after computerized tomography when necessary, but as proved by this series, it will be needed in a relatively small number of cases. These include patients with technically limited CT scans or those in whom the possibility of an associated vascular lesion of the cervical or intracranial vessel is clinically suspected. (3) It is essential to obtain CT scans of the best possible quality. Sedation will be required in many instances, but this is considered worth doing because a normal CT scan, without significant technical limitations, will exclude the presence of lesions requiring prompt surgical intervention. Those patients who require surgery will need general anesthesia under any circumstances. (4) There is generally a direct relationship between the severity of clinical presentation and the CT demonstration of the abnormality responsible for the clinical status. Seventy percent of the patients clinically diagnosed as contusion had positive CT scans, and for all practical purposes, 100 percent of patients having trauma more severe than our Group III (contusion) had abnormal CT scans. Likewise, the number and intensity of tissue abnormalities on CT scans increase proportionately with the severity of the clinical signs and symptons. (5) It is foreseen that, with the advent of faster computerized tomographic scanners, the usefulness of this method will increase further, owing to a reduction in the total examination time and the lessened requirement for sedation.
Some of the limitations of CT in the diagnosis of neurologic disease are reported. Problem areas include small lesions; lesions obscured by adjoining structures; small vascular structures and detail of large vessels; cases in which the diagnosis is made but information is incomplete for treatment; cases of incorrect diagnosis; non-nenoplastic lesions mistaken for neoplasms; some subdural hematomas; occasional false negative findings; and misinterpretation due to technical errors. Knowledge and use of the clinical presentation, the performance of other complementary diagnostic procedures, repeat CT scans tailored to the region of interest, and repeat serial scans may assist in reaching the proper diagnosis and diminishing potential error.
Metrizamide (Amipaque), a nonionic water soluble contrast agent, has been shown to be safe and efficacious for lumbar myelography. Clinical trials of cervical, thoracic, and even intracranial examinations have produced good results. Despite an inherent neurotoxicity, significant complications have been quite rare, and patient tolerance in general is remarkably good. Preliminary results of metrizamide cisternograms using hypocycloidal tomography are presented to illustrate the anatomic detail which can be demonstrated using this technique.
Metrizamide cisternography, combined with hypocycloidal tomography, has been performed in 12 patients with possible posterior fossa or parasellar mass lesions with finely detailed images of the basal cisterns resulting. Computed tomography was performed in nine of these patients and produced exceptional images of the cisternal anatomy. The technique of cerebrospinal fluid enhancement may be efficacious in identifying small basal masses not shown with conventional computed tomography, and thus may form an important complement to enhancement by intravenous injection of contrast medium.
Positron scintigrams were obtained in normal subjects and in patients with intracranial tumors and cerebral vascular disease, using a multicrystal positron camera. The radiopharmaceuticals were 68Ga complexed with adenosine triphosphate (68Ga-ATP), 13N-ammonia (13NH3), and 15O2. Six clinical cases are described to illustrate the different cerebral distributions of intravenously administered 68Ga-ATP, 13NH3, and inhaled 15O2. The possible value of these agents in the study of cerebral metabolism and in differential diagnosis of intracranial disease is discussed.
The findings and diagnostic results in 600 examinations of primary and metastatic intracranial neoplasms performed at one hospital with the EMI scanner are presented and the effectiveness of this method is compared with that of radionuclide imaging, cerebral angiography, and pneumoencephalography. The computed scan proved to be highly reliable in the diagnosis of glioma, cerebral metastases, meningioma, and acoustic neuroma.
CT has been found to be of value in cerbrovascular disease. In acute infarcts, the CT (before anticoagulation) excludes intracerebral hemorrhage. The CT may not exclude small petechial hemorrhagic infarctions (with negative cerebrospinal fluid). Angiography, otherwise, is more informative, disclosing ulcerative, irregular plaques, senosis, emboli, etc. In old infarcts, the CT may differentiate an old infarct from a tumor in a patient with focal seizures. Angiography and radionuclide scans are less informative. CT is a valuable investigative agent for clinico-anatomic correlation in cerebrovascular disease.
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