Biomedical subjects

H Imhof

Publications and source records attributed to H Imhof.

At least 271 records · Page 15Linked to original sources

PubMed1977

Noise reduction by radiographic magnification.

Effective noise in the rare-earth system can be substantially reduced by use of radiographic magnification technique. The basic imaging properties of the rare-earth system (Alpha 8-XM) and the medium-speed system (Par-RP) were evaluated by the Wiener spectra, modulation transfer functions, and H&D curves. The visibility of radiographic details was determined with simple test objects. Results indicate that, as the magnification increases, the effective noise in the rare-earth system is reduced, and that the visibility of small structures can be improved.

Models, Anatomic↗

PubMed1977

[Radiographic magnification technique with a high-speed rare-earth screen-film system (author's transl)].

The advantages of radiographic magnification technique - better detail recognition and improved contrast with an enlarged field of vision - should prove an important supplement to the properties of a high-speed rare-earth system - low-current intensity, low voltage, short exposure time and, consequently, lower irradiation dosage. Physical measurements of the Wiener spectral value, MTF and HD curve proved the superiority of the radiographic magnification technique in combination with a rare-earth screen-film system as compared with a conventional system (Dupont Par speed screen, RP films). Phantom radiographs confirmed these results. The clinical usefulness of this method was assessed with respect to the detection rate of gall-stones by means of oral cholecystography. Two out of 25 cases showed gallstones only following implementation of the radiographic magnification technique. This method seems to be particularly valuable in angiography. In 7 out of 18 abdominal angiograms and 4 out of 14 renal angiograms the number of visible vessel ramifications was greater with the magnification technique. In 5 cases valuable diagnostic information was revealed only by means of the magnification technique. Despite two-fold or 1.7-fold magnification, measurements of skin irradiation exposure showed a reduction of about half in comparison with conventional techniques. Reduced exposure to irradiation combined with improved detail resolution should ensure that this method receives an established place in routine radiodiagnosis.

Angiography↗

PubMed1976

[Retroperitoneal lymphangiodysplasia with exudative enteropathy. A case of cystic dilated cisterna chyli and splenic cysts].

In a 16 years old girl we found the syndrome of exsudative enteropathy with intestinal lymphangiectasy which differs from previous reported cases by several malformations of the lymphatic system. Besides changes in the intestinal lymphatics there was a retroperitoneal lymphangiodysplasia, a reduction and hypoplasia of the lymph vessels in the legs and cysts in the spleen. By substitution of albumin followed by a diet with middle chained triglycerids (MCT), serum protein was stablised but a relapse could not be prevented. Surgical treatment was not possible because the changes were too extensive. The value of diagnostic measures for differential diagnosis of the intestinal lymphangiectasy is presented.

Adolescent↗

PubMed1975

[Determination of regional ventilation-perfusion ratio with xenon-133].

Knowledge of the regional ventilation/perfusion ratio is of great interest for the diagnosis and therapy of disorders of pulmonary function. By injecting intravenously a bolus of Xe-133 during breathholding and by recording the influx of activity into the lung with a scintillation camera and analogue tape storage, the regional perfusion of the lungs can be determined, using the count-rate increase per unit time. Once the maximum count-rate is reached the patient is allowed to breathe normally. The slope of the count-rate decrease over the lungs is a measure of ventilation. The regional ventilation/perfusion ratio is calculated by dividing these two indices. Regional disturbances of the ratio are the most frequent cause of hypoxia. The demonstration of such disturbances are therefore of significance in the diagnosis and therapeutic control of pulmonary diseases.

Adult↗

PubMed1975

Bleomycin as carrier substance for 99m-Technetium in tumour diagnosis (author's transl).

99m-Tc-Bleomycin is a promising tool for scintigraphic imaging of some types of malignant tumours. The rapid decay of 99m-Tc, together with a high affinity of bleomycin for certain histologically-defined tumours recommends its use in humans. Moreover, by using high specific activities of bleomycin, no toxic effects are to be expected. At 00-C, the chelate of 99m-Tc and bleomycin is stable and its storage or transport are recommended at this temperature. Following the i.v. injection of rats with 99m-Tc-bleomycin, a high specific activity is found in the liver, spleen, lungs and skin. In view of its excretion by the kidneys an extremely high activity is found in the urogenital system. Scintigraphic imaging of lymph nodes in a case of Hodgkin's disease, of a embryonal carcinoma, of a thyroid carcinoma, of an astrocytoma and of a solid carcinoma was obtained in patients investigated by this method.

Adult↗

PubMed1975

[Pulmonary perfusion, ventilation, and gas exchange during modified cobalt-60 teletherapy of operated on breast carcinomas].

Post ablationem mammae, 22 patients were exposed to a modified telecobalt-irradiation because of mammary carcinoma. (Tangential pendulum irradiation of the thoracic wall with deflection of the central beam off the pendulum axis, parasternal irradiation with pendulum fields, irradiation of the supraclavicular and axillar area with deflection of the central beam to lateral and cranial directions.) During radiation therapy and up to six months after its termination, periodical pulmonary function tests were accomplished, consisting in a radiogram of the thorax, in spirometric check-up and blood gas analysis, and in an examination of pulmonary perfusion and ventilation using radionuclide techniques. In one patient with metastases to the ribs, the spirographic and nulear-medical ventilatory results changed for the worse in the course of time, whereas the other 21 patients did not show any significantly abnormal alterations at follow-up examinations.

Adult↗

PubMed1975

[Röntgen appearances of pulmonary edema and their clinical and physiologic correlates (author's transl)].

With the rapid increase in the number of intensive care units in surgical and medical departments knowledge of early radiologic signs of pulmonary edema gains in importance. On the basis of investigations by American authors typical changes in the distribution of pulmonary blood supply can be shown, in good correlation with pressure changes in the pulmonary vein in left heart failure. When pressure rises in the pulmonary vein the well-know changes of interstitial or alveolar (acinary) pulmonary edema arise. Differential diagnosis between pulmonary edema due to left heart failure and edema from other causes is aided on the one hand by the presence of interstitial pulmonary edema and redistribution of blood, on the other hand by the abnormaly large heart and configuration. Neither Röntgen appearances nor type of distribution of pulmonary edema are specific for any given cause. In all cases of pulmonary edema, the primary-peripheral excepted, clinical signs either occur later than X ray findings or will be absent altogether. Respiratory physiology permits, according to the severity of the edema, proof of hypoxemia with pronounced differences in the regional ventilation-perfusion quotient up to marked reduction of compliance and increase of resistance.

Heart Failure↗

PubMed1974