Search PubMed⌕ Search

Biomedical subjects

D Norman

Publications and source records attributed to D Norman.

At least 235 records · Page 13Linked to original sources
PubMed1981

Technical aspects and clinical applications of CT/X, a dynamic CT scanner.

CT/X is an X-ray computed tomographic scanner system designed for research in the clinical applications of rapid sequence scanning. The minimum scan time is 1.5 sec, and up to 18 images of the same cross section can be derived from scans taken over a 30 sec time interval. With this high image rate, the transit of a bolus of iodinated contrast medium can be followed through any cross section of the body. Rapid sequence scanning through a series of contiguous levels can also be performed, and 12 levels can be scanned in less than 50 sec. The short aggregate scan period minimizes the likelihood of interslice patient motion resulting in high quality multiplanar images. To fully exploit this capability, an imaging facility capable of reformatting axial transverse display data into a plane of arbitrary orientation has been incorporated into the system. A computer-electrocardiographic interface is also provided for use in retrospective cardiac gating. The capabilities of the scanner are illustrated with selective clinical studies.

Angiography↗
PubMed1981

Functional imaging of the brain using computed tomography.

Data from rapid-sequence CT scans of the same cross section, obtained following bolus injection of contrast material, were analyzed by functional imaging. The information contained in a large number of images can be compressed into one or two gray-scale images which can be evaluated both qualitatively and quantitatively. The computational techniques are described and applied to the generation of images depicting bolus transit time, arrival time, peak time, and effective width.

Brain↗
PubMed1981

Complete myelographic evaluation of spinal metastases from medulloblastoma.

Twenty-six patients with medulloblastoma had complete myelography and spinal fluid cytology and tests for polyamine levels in the evaluation for spinal metastases. The nature and location of abnormalities are presented in this report. Metrizamide was demonstrated to be safe and effective for complete myelography in children. The usefulness of myelography in detecting spinal metastases at the time of initial diagnosis (11%) and at the time of first intracranial recurrence (33%) is discussed.

Adolescent↗
PubMed1981

Dynamic computed tomography of the brain: techniques, data analysis, and applications.

Rapid sequence computed tomography (CT) scanning has many potential applications in studying intracranial physiologic events. However, visual inspection of these rapid sequence scans fails to extract the large amount of information inherent in the digital data. The concept of corrected mean transit time applied to rapid sequence scans after intravenous bolus injection of contrast material provides quantitative data on relative hemispheric flow. Use of histogram-based areas of interest permits accurate and reproducible identification of anatomic structures including arteries and gray and white matter. Gamma variate curve fit techniques reduce statistical noise. The concept of transit time can be expanded to the creation of functional CT images.

Blood Flow Velocity↗
PubMed1981

Selective venous sampling for ACTH in Cushing's syndrome: differentiation between Cushing disease and the ectopic ACTH syndrome.

We performed selective venous catheterization and sampling for ACTH in six patients with ACTH-secreting pituitary adenomas (Cushing's disease) and four patients with occult ectopic ACTH-secreting neoplasms. In five patients with Cushing's disease in whom the inferior petrosal sinus could be catheterized, ACTH levels were unequivocally higher than simultaneous peripheral values: The ratio was greater than 2.0, with a range of 2.2 to 16.7. In contrast, the inferior petrosal sinus-to-peripheral ACTH ratio in three patients with ectopic ACTH secretion was less than 1.5. In the fourth patient, an arteriovenous gradient of 6.8 was shown 2 years before a bronchial carcinoid tumor was clinically apparent. Central-to-peripheral ACTH ratios at the level of the jugular bulb and jugular vein were not diagnostic. We conclude that selective venous ACTH sampling from the inferior petrosal sinus is a reliable and useful aid in the differential diagnosis of Cushing's syndrome when standard clinical and biochemical studies are inconclusive.

ACTH Syndrome, Ectopic↗
PubMed1980

Multiplanar evaluation of the optic canal from axial transverse CT sections.

High resolution multiplanar images of the optic canal can be obtained using computer transformations of 1.5 mm axial transverse sections through the orbit. Parasagittal sections through the optic canal along the course of the optic nerve or sections perpendicular to the canal are easily and reproducibly obtained. This approach is a much more efficacious means of examining the optic canal both in terms of information yield and reduction in radiation dose.

Humans↗
PubMed1980

Radiography of trigeminal neuralgia and hemifacial spasm.

Radiographic findings in 68 patients with trigeminal neuralgia and 24 patients with hemifacial spasm are reviewed. The relative value of various radiographic diagnostic procedures is discussed. Trigeminal neuralgia and hemifacial spasm are usually caused by vascular compression of the trigeminal root entry zone and facial nerve exit zone respectively. Computed tomography (CT) of the posterior fossa is the only radiographic screening procedure required. Angiography should be reserved for patients in whom CT findings suggest an aneurysm or tumor.

Adult↗
PubMed1980

Prognostic significance of the pretreatment CT scan on time to progression for patients with malignant gliomas.

Case histories of 61 patients receiving multimodality therapy for primary malignant brain tumors were reviewed for factors visible on the computerized tomography (CT) scan that correlated with the interval of time from diagnosis and pretherapy evaluation to the time of documented tumor progression. The initial pretreatment CT scan of each patient was reviewed. Midline shift, peritumor low density (edema), the greatest diameter of tumor enhancement, and the greatest diameter of the intratumor low-density area were measured prior to radiation therapy and chemotherapy. Using a Weibull survival probability model, time to tumor progression was most satisfactorily fitted using two covariates, the volume of enhancing tumor (for instance, contrast-enhancing tumor less intratumor low density), and the presence of a peritumor low-density area. Patients who exhibited a small amount of contrast-enhancing tumor with peritumor low density tended to have a longer time to progression than patients with large contrast-enhancing tumor volume and no peritumor low density. Midline shift was not as important a variable as the extent of tumor contrast enhancement or peritumor low density.

Brain Neoplasms↗
PubMed1980

Cysts in malignant gliomas. Identification by computerized tomography.

The clinical course, computerized tomography (CT) scans, and postmortem reports for 265 patients treated for malignant brain tumors were reviewed. Forty-one patients underwent reoperation for tumor recurrence and one had needle aspiration as a diagnostic procedure; of these patients, seven (3% of 265 and 17% of 42) were diagnosed as harboring tumor cysts and 10 (25% of 41) as having necrotic tumor centers. The CT scans on the 17 patients harboring tumors with surgically confirmed cysts and necrotic centers were reviewed; criteria for distinguishing between cysts and central necrosis are suggested. The relative benefits of repeated aspiration and surgical therapy for these cystic lesions are discussed.

Astrocytoma↗
PubMed1979

Fluid--fluid level in cystic cerebral metastatic melanoma.

Two cases of cystic metastatic melanoma are presented. The only reliable computed tomography sign of a true cystic lesion is the presence of an interface, such as between blood and tumor fluid. Differentiation of cystic metastatic melanoma from other cystic lesions of the brain is discussed.

Adult↗
PubMed1979

Computed tomography in primary reticulum cell sarcoma of the brain.

The CT findings in 16 patients with histologically proved primary central nervous system (CNS) reticulum cell sarcoma (RCS) showed this malignancy to have predilection for the basal ganglia and thalamus, the periventricular white matter, the corpus callosum, and the vermis cerebelli. In 43% of patients with untreated tumor it presented as multifocal lesions; in each of these patients the basal ganglia were involved in conjuction with another site. In the other 57% of patients with untreated tumor presenting as solitary lesions the basal ganglia, the corpus callosum, and the frontal lobe were sites of predilection. Such solitary lesions may be indistinguishable from other tumors. Contrast enhancement of RCS was characteristically homogeneous with rare lucency, even in very large lesions.

Adolescent↗
PubMed1979

Metrizamide and radionuclide cisternography in communicating hydrocephalus.

Simultaneous 111In-DPTA and metrizamide CT cisternography correlated closely in the qualitative imaging of cerebrospinal fluid (CSF) dynamics in 9 normal patients and in 11 patients thought to have communicating hydrocephalus. CSF clearance of both tracers was similar; significant absorption occurred in the spinal dural sac. Although delayed elevated serum iodine levels correlated highly with abnormal persistent ventricular penetration (detection at 48 hours), these levels cannot be used to predict abnormal ventricular stasis. The pattern of ventricular and cortical sulcus enlargement on the plain CT scan did not indicate whether the dynamic metrizamide cisternogram would be normal or abnormal.

Cisterna Magna↗
PubMed1979

The role of computed tomography in the evaluation of neck masses.

Application of computed tomography (CT) to neck masses has received little attention. The authors reviewed 10 cervical masses studied with CT as well as conventional imaging modalities. CT was extremely useful in defining both the osseous and soft-tissue extent of the lesion. In several instances, CT was able to show the relationship of the tumor to the spinal canal. When combined with angiography, CT demonstrated the relationship of the major cervical vascular channels to the lesion. Pathological conditions included neurofibroma, chordoma, branchial cleft cyst, neuroblastoma, lymphoma, neurilemmoma, and metastatic carcinoma.

Adult↗
PubMed1979

Computerized tomographic diagnosis: pitfalls for neurosurgeons.

Computerized tomography as a diagnostic procedure is characterized by its high sensitivity but limited specificity. This lack of specificity may result in an erroneous diagnosis and, possibly, in ill-advised therapy unless clinical and objective data are carefully considered in interpreting the study. The most common pitfalls encountered are the phenomena of contrast enhancement of infarcts and mass effect associated with infarcts. Many different pathological processes can have similar enhancement patterns. The evolution of high density, acute hemorrhage to isodense areas in the chronic hematoma can become a serious diagnostic problem unless an appropriate history is available. The authors discuss 30 cases in which misinterpretation of CT scans resulted in erroneous diagnoses. Seventeen of these patients underwent operation.

Adult↗
PubMed1979

Computerized tomography and pathological correlation in cystic meningiomas. Report of two cases.

Meningiomas have been reported to have associated areas of surrounding low density on computerized tomography (CT). These low-density areas may represent edema, widened subarachnoid spaces, loculated cerebrospinal fluid, demyelination, or adjacent tumor. Two cases are presented in which this adjacent area of low density represented a tumor cyst. Recognition is important as the CT appearance of these lesions may simulate a metastatic tumor.

Humans↗