PHYSICAL PARAMETERS FOR THE APPLICATION OF MRI - RESTRICTIONS DUE TO PHYSIOLOGICAL CONSEQUENCES AND GUIDELINES

Purpose:The standards and regulations concerning the protection of pat ients acid operator staff within the context of MRI are compiled. Resu lting consequences regarding physical parameters are evaluated. Materi al and methods: The static magnetic field, heating effects caused by R F-fields and acoustical noise are outlined. The actual boundaries of t hese parameters are compared against the relevant published standards. Peripheral stimulation limits due to pulsed gradient fields have been determined in a new clinical study. Results: Many parameters recommen ded for the normal operating mode are already exceeded during routine MRI. Referring to our clinical study, we found that limits recommended in the MRI relevant standards are unnecessarily conservative and can actually be doubled. Conclusions: The applicable national and internat ional standards and regulations show (at least partly) that serious di fferences in the definition of terms and values exist. The application of these standards would be much easier if they were made uniform. Th e values defined in the MR-specific standards should be adapted to act ual knowledge concerning patients' safety.