Biomedical subjects
Publications and source records attributed to S Schuy.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
In glioblastoma multiforme and high-grade astrocytomas the following procedure has been implemented to try and prevent recurrence: after extirpation of the tumour its bed is lined with metal powder and the patient's head is exposed to a high-frequency magnetic field every 4 weeks. As a result the temperature is raised by induction to +45 degrees C at the boundary between metal and brain tissue. This ought to be sufficient to prevent tumour recurrence. Varied results were achieved using this technique in 103 patients.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Experience shows that both in the evaluation and in the purchase of ultrasonic scanners the subjective impression of the images plays a dominant role. The image intelligibility is investigated via tissue equivalent test phantoms and quantitatively analysed using the ROC (Receiver Operating Characteristic) method. Comparison of devices of different price categories shows that this investigation is an important addition to the analysis of image fidelity, provides additional important data for a comprehensive comparison of devices, and allows an objective determination of the price-benefit relation.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The development of ultrasonic imaging techniques is by no means finished even today. The morphological display of anatomical cross-sections has already reached a high standard and is characterized by the realization of real-time compound scanners. Automated water-bath scanners, either compound or single pass, are intended to help ultrasound to play a more dominant role in mammography, especially as a screening method, although at present it cannot be used very efficiently for this purpose. Considerable progress can be expected with the increasing use of computer facilities, especially digital signal-processing techniques. They should not only further improve image fidelity and intelligibility, but also the comfort of the handling. A major step forward will be the implementation of objective transducer-independent tissue-differentiation facilities into imaging devices. The development of alternative ultrasonic imaging techniques like the transmission camera should increase the scope of ultrasonic application rather than compete with B-scan imaging.
The liquification of the corpus vitreum by ultrasound is a promising new alternative to presently used mechanical methods of vitrectomy. With regard to the duration time of insonation, as well as to the ultrasonic intensity, there exist thresholds, the exceeding of which causes a discontinuous breakdown of the vitreous frame in a spherical zone around the transducer tip which can be verified by ultrasonic pulse echo methods. Viscosity measurements showed that the vitreous isonified in this area has almost the same viscosity as water whereas its optical transparency remains unchanged. The dependence of the diameter of the liquified zone on insonation time was measured.
The investigations concerning the influence of supply-frequent electric fields on man have been carried out on 12 subjects in 24 single trials. A field intensity as it occurs in the height of the subjects' head under a 380 kV high voltage transmission line was used. Some physiological parameters like ECG, EEG, blood pressure, blood gas and reaction time have been recorded and analyzed. The parameters were both analogously recorded and digitally stored as indicated in Fig. 2. Some of the investigations were carried out under mental load of the subjects and showed that the changes in the heartrate due to this load cover the switch-off effect of the heartrate. For the other parameters like EEG, reaction time, blood gas and blood pressure no influence of the investigated field intensity on man could be found.
EEG was recorded simultaneously from several scalp regions in 5 normal subjects and analysed, using a PDP 11/45 computer by means of an autoregressive model. Significant intra- and interhemispheric differences in the peak frequencies within the alpha band were observed, up to 0.8 c/sec. Local modality -dependent increases in the peak frequency were also observed, which were predominant in occipital areas during visual stimulation and in central regions during acoustic stimulation. In most cases an increase in the peak frequency occurred together with a marked decrease in power, which could be interpreted as a desynchronization of slow components within the alpha band. These peak frequency differences found in the scalp EEG lead to the assumption that there might also be different alpha rhythms at the level of the cortex.
Explore the source record for details and available documents.
On 12 voluntary subjects with normal visual function the intraocular pressure was increased dependent on the ophthalmic blood pressure Pm = (Ps + Pd)/2. The visual field was tested under this pressure load by means of a subjective method and the visual evoked potential was derived under light and dark adaptation. Comparison of subjective and objective investigations demonstrated that the different visual evoked potentials which are dependent on the state of adaptation are a measure for the pressure sensibility of prelaminar optic nerve fibers.
Explore the source record for details and available documents.
Electroretinograms of 19 human eyes in light- and darkadapted state under normal and increased intraocular pressure (increased by a spring pressure dynamometer) were recorded (Pm = (Ps + Pd)/2). On physiological intraocular pressure the a-wave showed a low increase in amplitude after 25 min of dark adaptation, the b-wave a great one. After increasing the intraocular pressure no significant influence of the state of adaptation to the magnitude of the a- and b-wave could be found.
Explore the source record for details and available documents.