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Biomedical subjects

A Ganssen

Publications and source records attributed to A Ganssen.

11 recordsLinked to original sources
PubMed1995

[Safety aspects in MR imaging].

With the growing number of Magnetic Resonance Systems in operation in clinical practice, safety aspects gain increasing importance. Therefore, it is necessary to evaluate possible risks and effects on human health. After an introduction to the basic principles and techniques involved, the various effects on biological systems and especially the human organism caused by the static magnetic field, the alternating magnetic fields and the high frequency fields required are described on the basis of current literature and partially also on our own experience. Basic information for the safe operation of diagnostic Magnetic Resonance Systems is presented. Limits for exposure to magnetic fields and time-dependent changes of electromagnetic fields for patients and employees as suggested by health authorities are given.

Contraindications↗
PubMed1993

[Depiction of evoked regional brain activity using magnetic resonance tomography].

After brief summary of the various parameters determining contrast behaviour in diagnostic magnetic resonance imaging, special attention is paid to recent developments in its application to the study of brain perfusion and oxygenation. With and without extrinsic contrast media, it is now possible to image regional tissue perfusion and brain oxygenation and thus the evoked activation of regions of the brain with a high spatial resolution of about 1 mm and a temporal resolution of about 50 ms. The blood oxygenation dependent magnetic properties of hemoglobin are used as sensitive endogenous indicators of the oxygenation state of blood. In dependence upon evoked local brain activity, contrast changes of up to 30% have already been observed. Possible future developments with respect to the application of MRI to even more complete functional studies of the brain and other organs will be mentioned.

Brain↗
PubMed1981

[Early clinical experience with nuclear magnetic resonance (author's transl)].

Previous work on adults with carcinomas, benign polyps, postoperative changes or inflammatory or radiation induced swellings in the facial skeleton has shown that it is possible to demonstrate the local anatomy, and particularly the orbits and sinuses without subjecting the patients to radiation. Differentiation between fat, oedema and malignant tissue appears to be possible, as has been demonstrated by our early cases. Early attempts at examining the trunk could only be carried out in infants. These suggest that in the thorax and abdomen differentiation of anatomical structures is not possible. The value of nuclear magnetic resonance in clinical diagnosis is still uncertain. Its advantage depends on the ability to differentiate tissues because of their varying water content. It raises the possibility of differentiating soft tissues by a non-invasive method and without using radiation. Further investigations are necessary in order to evaluate the clinical usefulness of the new technique. The physical basis of the method, compared with conventional radiology, permits only guarded optimism.

Aged↗
PubMed1981

[Nuclear magnetic resonance tomography].

Imaging methods based on nuclear magnetic resonance allow the production of sectional images of the human body without ionizing radiation. It is possible to measure the density and relaxation times of the water protons in body fluids or tissue. This allows not only to obtain morphological information but also to get some insight into the spatial distribution of physiological data. Starting with a review of the principles of nuclear magnetic resonance it is explained how the measured signal can be associated with an image point; it is also explained what type of apparatus is necessary and what the physical limitations are. Possible risks the patient may be exposed to in an examination using nuclear magnetic resonance are discussed. The present state of the technical development enables the production of whole-body sectional images of a living person within about one minute. By means of some typical examples the nature and properties of these images are explained. Although extensive clinical studies will be necessary before a more general assessment can be made of this method, an outlook is provided on expected further developments and possible future fields of application.

Humans↗