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Biomedical subjects

O H Wegener

Publications and source records attributed to O H Wegener.

11 recordsLinked to original sources
PubMed1979

[Quantitative mineral estimations in vertebral bodies by computer tomography (author's transl)].

The accuracy of computer tomographic bone density measurements in the axial skeleton was tested by comparing results obtained from the first lumbar body in abdominal phantoms. An almost linear relationship (r = 0.998) was found between increasing concentrations of a calcium chloride solution and CT absorption values. The sum of the CT values of sections through the vertebral body correlated well with their ash content (r = 0.90) as well as with the hydroxyl apatite values obtained by I125-absorption densitometry (r = 0.88). Reproducibility of CT measurements on the phantom was good (coefficient of variation = 1.2% in the spongiosa). Average CT values of separate measurements of the spongiosa and cortex could be correlated with the total spongiosa by a special programme (r = 0.95). In the practical application of this technique, possible sources of error must be considered, such as the effect of high energy polychromatic radiation, inhomogeneity of the object being investigated and difficulties in positioning the patients

Absorptiometry, Photon↗
PubMed1979

[Extension of thoracic roentgen diagnosis by computer tomography (author's transl)].

In 400 examinations of the thorax results of computer tomography were compared with respective pa chest films and conbentional tomograms. In the peripheral areas of the lung, interstitial parenchymal alterations and metastases were better visualized by CT. The size of central bronchial carcinomas and space-occupying lesions of the thoracic wall can be determined with greater accuracy by CT. Primary tumors, lymphnode enlargement and vascular alterations can be differentiated and localized more precisely by CT. The size of the heart chambers, intracavitary tumors as well as septal and myocardial wall thickness can be determined non invasively.

Aortic Aneurysm↗
PubMed1978

[Computer tomography of the mediastinum (author's transl)].

The scope and limitaitons of computer tomography in the diagnosis of diseases of the mediastinum were studied, using a 20 seconds scanner (EMI CT 5005/12). The mediastinal structures can be accurately differentiated and diagnosis is therefore frequently facilitated. In addition to a knowledge of the anatomy, it is important to be familiar with various types of artefact since these may change the degree of attenuation. Additional use of contrast medium is frequently required.

Aortic Aneurysm↗
PubMed1978

Measurement of lung density by computed tomography.

Computed tomography scanners can be calibrated to provide reproducible measurements for a quantitative analysis of lung density. Typical histograms for inspiration and expiration are presented. The reproducibility of the method is demonstrated as well as the limitations caused by artifacts and incomplete inspiration. This method is suggested for follow-up studies of patients with diseases affecting the entire lung. Early detection of interstitial lung disorders also seems possible.

Absorptiometry, Photon↗
PubMed1977

[Whole body computer tomography: principle-purpose - requirements (author's transl)].

After explaining the principle of whole body computer tomography the field of indication is outlined with reference to some of our own experiences. Up to now, it has proved its value in the following indications: preoperative diagnosis, supplementing pulmonary radiodiagnosis, substitution of invasive diagnostic procedures in mediastinal diseases, clarification of diseases of the abdominal cavity, of space-occupying processes in the kidney, in the true pelvis, and detection of retroperitoneal processes. The financial expenditure for this novel method of investigation is described according to a formula. The cost of given or estimated numerical values show the importance of adequate usage. The added costs for a second personnel shift for an examination rate of more than 7 patients a day are trivial because of the high basic expenditure.

Abdominal Neoplasms↗
PubMed1977

[Demonstration and recognition of microcalcification on xeromammograms (author's transl)].

The ability to demonstrate detail and to recognise microcalcification on xero-radiographs was investigated experimentally under conditions resembling those in actual practise; the results were compared with those of film mammography, and evaluated quantitatively. Xero-radiographs were slightly better, but in general were comparable in their ability to demonstrate microcalcification. The effect of the quality of the radiation and of geometric factors is discussed, and size of the smallest recognisable particles is given. Problems of optimal exposure in xero-radiography are discussed.

Breast Diseases↗
PubMed1977

[Contrast and exposure in xeroradiography (author's transl)].

Systematic sensitometric measurements of xero-radiographs were carried out and compared with ordinary X-ray films. The effect of kilovoltage and exposure on image contrast and resolution was investigated; optimal exposure and kilovoltage were sought and sources of loss of information are pointed out.

Technology, Radiologic↗