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Biomedical subjects

P Rieder

Publications and source records attributed to P Rieder.

8 recordsLinked to original sources
PubMed1992

[Optimization of filtration and lighting parameters in pictures of the hand using digital luminescence radiography].

The appearance of digital radiographs were markedly influenced by post-processing. To optimise images of the hand, radiographs of 7 patients with arthritis were modified by various filters. 6 observers evaluated the presence or absence of erosive changes during an ROC study and the advantages of low filtration were demonstrated. Further images were prepared of anatomical preparations in which para-articular defects had been made and of a hand phantom covered in perforated plexiglass. Limited filtration and low enhancement factors again provided the best results. Dose reduction of 50% resulted in a significant deterioration in the ability to recognise erosions and artificial lesions.

Arthritis↗
PubMed1991

[Ozone, ventilatory function and bronchial reactivity].

Forty adult hospital workers were followed prospectively in 1989 by monthly assessment of the lung function and bronchial responsiveness to methacholine in a rural region in Switzerland. No correlation was demonstrated between these values and the concentrations of tropospheric ozone. Nevertheless, this is not incompatible with previous studies showing impairment of ventilatory function in subjects exposed to ozone, for several reasons: ozone levels in 1989 were low, the indoor concentrations were lower than outdoors and the volunteers performed little or no physical activity.

Adult↗
PubMed1990

[Pathologic dens fracture in irradiated malignant neurofibroma].

A pathological dens fracture in a 47 year old patient with malignant neurofibroma is described. These tumours are very rare but the prognosis is very poor because of rapid proliferation and early metastatic progression. In the described case, bone osteolysis remained unnoticed until manifestation of clinical symptoms. The pathological fracture occurred despite irradiation of the dens.

Axis, Cervical Vertebra↗
PubMed1989

Intravenous DSA and dynamic computed tomography for postoperative follow-up of type A aortic dissections.

We undertook a direct comparison of intravenous digital subtraction angiography and dynamic computed tomography in a follow-up study on 37 patients who had undergone surgery on the thoracic aorta for acute or chronic type A dissections. These are minimally invasive and complementary procedures: IV-DSA provides a clear angiographic image of the dissection, with visualization of the true and false channels, their distal extension and the supra-aortic and abdominal vessels they supply. Dynamic CT best demonstrates the proximal extension of the disease; it visualizes clotting in the false lumen and permits a more accurate measurement of the aortic width, and thus early recognition of a developing aneurysm.

Adult↗
PubMed1986

[Suitability and comparison of compensating filters for thoracic diagnosis].

The effect of three types of filter on the quality of radiographs of the chest was compared. These filters improve visualization of mediastinal structures without significantly reducing the quality of the pulmonary image. In practice the Du Pont filter proved best; the quality of the central and peripheral portions of the lung image is equal to that of an ordinary radiograph and visualization of the mediastinum is improved. The Agfa-Gevaert filter showed no significant disadvantages compared with the ordinary techniques but the improvement in mediastinal visualization is not that marked. The 3 M filter yields poor images of the central portions of the lung and its type of construction prevents the retrocardiac structures from being pictured as well as with the other filters.

Humans↗
PubMed1986

[Percutaneous transluminal irradiation of biliary tract cancer using iridium].

In ten patients with biliary carcinomas, percutaneous biliary drainage was instituted and intracavitary irradiation performed, using 192iridium with a dose of 40 to 80 Gy. Eight of these patients had been found to be inoperable at laparotomy and two had had a recurrence. In half the patients there was a reduction in the degree of stenosis due to the tumour, but in only one patient was it possible to remove the draining catheter. Survival time in eight patients was between one and eight months, average 5 months. Two patients survived for eleven and twelve months respectively. The relatively poor results are due to extensive metastases. On the other hand, there can be no doubt about the effectiveness of this treatment on locally confined tumours, in view of the reduction in the obstruction caused by the tumour.

Adult↗