15 Fakultätsübergreifend / Sonstige Einrichtung
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Item Open Access Beam/ray imaging(1988) Nagel, Joachim H.The diagnosis of disease is facilitated by imaging internal structures of anatomy and metabolic processes. The basic medical imaging techniques are radiographic (X-ray) imaging, nuclear medicine (gamma-ray) imaging, magnetic resonance imaging (MRI), ultrasound (US) imaging, and endoscopy. With the exception only of ultrasonic imaging, these techniques use electromagnetic waves as information carriers or measuring probes. According to the nature and wavelength of the radiation used and the properties of its interaction with tissue, including its ability to penetrate, specific diagnostic applications and imaging principles have been developed for each type of radiation.Item Open Access Recording of uterine activity from the abdominal lead EMG(1980) Nagel, Joachim H.; Schaldach, MaxWith external tocography some form of pressure or force transducer is fastened to the abdominal wall by means of an elastic belt. Uterine contractions produce changes in the displacement of a sensor pin which acts on the transducer, producing an electrical signal that corresponds to the relative uterine pressure. External tocography, however, has the drawback that it is subject to many factors which may influence the results of the measurement. We feel that the limitations of tocography cannot be eliminated by technical improvements of the measuring equipment, and therefore the possibility of recording the uterine contractions from the abdominal lead electromyogram (EMG) without losing any information regarding tocography has been studied. As a result of the study it has become evident that the recording of uterine activity using the EMG is more reliable than tocography and offers even additional information about the excitation and propagation of the contractions. The basic methods that have been developed and the results of clinical tests are presented here.Item Open Access The non-invasive assessment of the uterine activity(1983) Nagel, Joachim H.; Schaldach, MaxAll in all, uterine myographic recording has proved valuable in clinical trials. On account of the high information yield and the simplicity of handling, in particular for the simultaneous recording of fetal and maternal heart activity in addition to the uterine contraction curve, the procedure described is highly suitable for clinical routine work. The combined recording of the electrical activity of the myometrium and the intrauterine pressure will, it may be presumed, provide more information about the behaviour of the uterine musculature than either technique alone.Item Open Access Processing the abdominal fetal ECG using a new method(1980) Nagel, Joachim H.; Schaldach, MaxThe performance of the method described above has been assessed in clinical trials. Comparing the results with those obtained using the earlier techniques of abdominal ECG processing showed a mean increase in the detection rate of the fetal QRS complexes of about 60%. When compared to fetal heart frequency recordings using ultrasonocardiography or phonocardiography the new method shows an important improvement with respect to the evaluation of short term variations of heart frequency.In addition to a bad signal to noise ratio the analysed abdominal signal showed a high rate of coincidence between maternal and fetal QRS complexes. Using simple threshold logic the measurement is obtained if the maternal ECG is subtracted prior to the threshold analysis of the signal. However, the necessary reliability is only achieved when both the maternal ECG is eliminated and a correlation analysis of the residual signal is performed. Comparing the FHF computed simultaneously from the scalp-lead ECG (A) and the abdominal ECG (8) shows that in most cases there is no loss of information when using the new non-invasive technique. In conclusion, it can be stated that the reliability of 'beat-to-beat' measurement of the fetal heart frequency could be significantly improved by employing the new analysis procedure. the resulting FHF curve cannot be employed clinically. An improvement of the measurement is obtained if the maternal ECG is subtracted prior to the threshold analysis of the signal. However, the necessary reliability is only achieved when both the maternal ECG is eliminated and a correlation analysis of the residual signal is performed.Item Open Access Biotelemetry(1988) Nagel, Joachim H.Telemetric transmission of functional and physiological information offers many advantages in medical diagnostics and patient surveillance. The telemetric data link avoids direct connections to the recording or monitoring equipment, which are sometimes embarrassing and restraining, thus leaving the patients freely movable. They can be monitored in their natural environment and during work. Accordingly, the measurement does not influence the physiologic system under study, thus avoiding severe artifacts. This advantage is especially important in behavioral studies involving both humans and animals. Implantable telemetry systems transmit internal physiologic signals, or serve to control and program implanted devices, such as stimulators and drug infusion systems, without the need of transcutaneous wire connections which always carry the risk of infection.