Sicherheitsaspekte bei der Anwendung magnetischer Resonanzverfahren in der medizinischen Diagnostik

[Measurement of MRI scanner noise]

The present paper describes a simple method for the analysis of MRI scanner noise. Besides the heating of body tissue by strong RF radiation and the formation of circular currents in the body induced bey switching field gradients, a noise level of more than 100 dB(A) during the measurement belongs to the potential risks of MRI. This risk is of particular concern for staff and accompanying persons who remain close to the scanner for different reasons (e. g., monitoring of anesthetized patients, reassuring of children). For this reason, and given the scanty information on noise provided in the manuals of the scanners, it is useful to quantify the noise level more exactly. This applies also to the evaluation of different sound-reducing methods for the patient. This presents the results of noise level measurements in the tomograph and in its surrounding, with and without noise reduction by headphones.

[Safety and safety limits in MRI]

The influence of electromagnetic fields on humans through the use of magnetic resonance tomography is an ongoing topic in the scientific literature. However, the contents of relevant standards and legal regulations governing the operation of MR equipment are less well known. We summarize the actual status and give an overview of the national and international bodies in charge of generation and publication of guidelines and regulations.

[Safety aspects in interventional MRI]

Because of its high soft-tissue contrast, Magnetic Resonance Imaging (MRI) is used increasingly for guidance and control of minimal invasive and neurological surgical procedures. Besides common precautions during an MRI investigation, special attention has to be paid to the consequences of MR compatibility, accuracy of localisation of interventional tools and geometrical distortions. As a new application of interventional MR intravascular procedures are developing that involve the introduction of guidewires, catheters and miniaturized coils with their leads into the blood vessels. Resonant currents and high electric fields can develop at the conductor ends, possibly causing burning lesions.