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Biomedical subjects

F J Hahn

Publications and source records attributed to F J Hahn.

At least 37 records · Page 2Linked to original sources
PubMed1984

Ocular volume measured by CT scans.

Newer CT scans have greatly enhanced oculometric research and made it possible to measure ocular dimensions. With these measurements, ocular volume can be more accurately estimated to understand its relationship with age and sex. One hundred CT orbit scans with presumed normal eyes were used for the data base. The mean values and normal variations of ocular volumes at various ages in both sexes are presented. Rapid growth of the eyeball was noted during the first 24 months of age. It reached its peak between the ages of 18 and 30 years of age, after which there was a reduction. Results may be of help in recognizing eye abnormalities such as microophthalmus and macrophthalmia.

Adolescent↗
PubMed1984

CT measurements of cranial growth: normal subjects.

Growth patterns of the cranium measured directly as head circumference have been well documented. With the availability of computed tomography (CT), cranial dimensions can be obtained easily. The objective of this project was to establish the mean values and their normal variance of CT cranial area of subjects at different ages. Cranial areas and its long and short axes were measured on CT scans for 215 neurologic patients of a wide age range who presented no evidence of abnormal growth of head size. Growth patterns of the cranial area as well as the numeric product of its linear dimensions were determined via a curve fitting process. The patterns resemble that of the head circumference growth chart, with the most rapid growth observed in the first 12 months of age and reaching full size during adolescence. It is believed that the availability of such reference, in addition to the head circumference measurement, will be valuable to the CT reviewer in determining the growth status of head size.

Child, Preschool↗
PubMed1984

CT measurements of cranial growth: microcephaly.

Computed tomographic (CT) head scans were measured to determine the cranial dimensions of four children with microcephaly. These measurements were compared with cranial dimensions of normal children. CT proved to be useful in determining the developmental status of children with neurologic problems relative to their normal counterparts on the basis of cranial dimensions.

Child↗
PubMed1978

The overshoot artifact as an aid in differentiating low densities on the computed tomographic scan.

This brief report describes an artifact that is seen as a thin, white rim outlining an air collection on the EMI 80 X 80 and 160 X 160 matrix CT scanners. This artifact is not associated with fat density and, therefore, its recognition allows presumptive differentiation between air and fat densities. The attenuation numbers of the lesion should then be obtained for confirmation.

Adipose Tissue↗
PubMed1977

Scintigraphic findings in hyperostosis frontalis interna.

Transient diminution of activity was seen on early radionuclide images of the brain in 5 patients with hyperostosis frontalis interna and filled in on subsequent studies. Radiographs confirmed the diagnosis. In 3 patients the changes corresponded extremely well with both modalities. This entity should be considered when diminished activity is seen in the frontal area.

Aged↗
PubMed1977

Thromboembolic complications of angiography for peripheral arterial disease: prospective assessment by Doppler ultrasound.

The incidence of thromboembolic arterial complications related to percutaneous angiography done for patients with arterial disease was assessed in 101 cases (105 procedures). There were 2 instances of anterior tibial artery obstruction and 3 of a decline in ankle pressure greater than 20 mmHg in patients with preexisting leg arterial disease. No patient evidenced symptoms of the complications. This incidence of thromboembolic accident, detected by Doppler ultrasound, is significantly less than those incidence rates noted previously, although the reasons for this difference have not yet been established.

Adult↗
PubMed1977

Renal lymphoma simulating adult polycystic disease.

Multiple cyst-like involvement of the kidney in a patient with lymphocytic lymphoma is presented. Both kidneys demonstrated the swiss-cheese appearance on nephrograms, simulating a typical adult type of polycystic disease. No tumor vessels or strains were noted.

Adult↗
PubMed1977

Computed tomography in cerebral hemiatrophy.

The clinical and radiographic findings in four cases of cerebral hemiatrophy are presented. CT findings reflect the underlying gross pathologic changes and are in agreement with those seen on plain skull radiography and pneumoencephalography. The most impressive finding was unilateral loss of cerebral volume with ipsilateral displacement of the midline structures. The differential diagnosis primarily includes Sturge-Weber syndrome and linear sebaceous nevus syndrome. The recognition of compensatory calvarial changes should indicate that the cerebral abnormalities are the result of an atrophic or hypoplastic process that began in early life.

Adolescent↗
PubMed1976

The excessively small ventricle on computed axial tomography of the brain.

Computed axial tomography has made it possible to observe excessively small ventricles in a variety of disorders of the CNS. This finding is presumably due to non-specific and diffuse swelling of brain parenchyma, and is illustrated in cases of trauma, neoplasm, encephalitis, pseudotumor cerebri, metabolic disorder, and probable dilantin effect. It is likely that other causes will be encountered in the future.

Adolescent↗
PubMed1976

Brain image manifestation in the patient with cavernous sinus occlusion.

Radionuclide findings in a case of cavernous sinus occlusion by an intracavernous aneurysm are described. A brain image obtained 10 minutes after injection of 99Tc pertechnetate shows diminished activity in the area of the right cavernous sinus and increased activity in the area of the right sylvian veins; these are attributed to abnormal venous blood flow and may serve as a sign of cavernous sinus occlusion.

Cavernous Sinus↗
PubMed1976

Frontal ventricular dimensions on normal computed tomography.

The computerized axial tomographic examinations of 200 normal patients and volunteers between the ages of ten to 81 years were evaluated. Determination of the ratio between the width of the brain and a dimension representing the distance between the outer borders of the lateral ventricles was made at two levels. This ratio, the cerebroventricular index, seems to be a reliable indicator of ventricular size. The standards vary with the age of the patient.

Adolescent↗
PubMedDate not supplied

Increased intracranial pressure as a complication of unilateral radical neck dissection in a patient with congenital absence of the transverse sinus.

We report a patient with increased intracranial pressure occurring after unilateral neck dissection. Subsequent vascular studies reveal a hypoplastic contralateral transverse sinus drainage and occlusion of the ipsilateral jugular bulb. We review the literature on the etiology of this vascular malformation and conclude that vascular anomalies of the venous drainage of the head be considered whenever postoperative signs of increased intracranial pressure occur after unilateral radical neck dissection.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Peripheral signal void ring in giant vertebral aneurysm: MR and pathology findings.

Thin, signal void rims have been noted to surround intracerebral hemorrhages and ruptured intracranial aneurysms on magnetic resonance imaging. Proposed mechanisms include hemosiderin deposition in macrophages and high blood flow. The authors describe an example of a thick, signal void ring in a peripheral luminal thrombus of a giant vertebral aneurysm.

Aged↗
PubMedDate not supplied

Percutaneous discectomy using the electromagnetic field focusing probe. A feasibility study.

The EFF probe has the capability of sharply focusing the eddy currents produced in tissue secondary to the electromagnetic field it generates. This sharp convergence of eddy current produces intense heat at the point of contact of the probe to the tissue, which can vaporize tissue. The probe diameter can be as small as required which makes it easy to be navigated into disc space for disc vaporization. Four discs were vaporized in three pigs by inserting the probe into the disc and vaporizing it. The vertebral columns were removed and transverse sections through the disc were made. Excellent disc vaporization was observed with vaporization of 70-80% of the nucleus. As the probe can be of flexible material it could be turned in different directions to vaporize necessary disc material.

Animals↗