Gec-marconi Limited

Anthony J Salloway

David John Gilderdale

In a magnetic resonance apparatus including a transducer (25, 31 ) positioned in the examination region of the apparatus, the transducer is connected with equipment (49) outside the examination region by way of a lead (47) which is grounded (51, 53) to signals of the frequency of the RF field applied to a subject (5) in the examination region to excite magnetic resonance in the subject, at a distance along the lead from the transducer equal to a quarter wavelength at the RF field frequency (or an odd multiple thereof). Distortion of the RF field due to loading by the transducer is thereby reduced. The transducer may, for example, be a microphone or loudspeaker, e.g. incorporated in an intercom or active noise reduction arrangement, or a sensor for sensing a condition of a patient being examined.

Reduction of RF field disturbance in magnetic resonance apparatus

In a magnetic resonance apparatus including an active noise reduction arrangement (9, 49, 51, 53) for use by a patient (5) undergoing examination in the apparatus the transducers (25, 31) of the arrangement are non-magnetic, e.g. are of the electret, piezoelectric or condenser type, and have no parts of ferromagnetic material.

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Northamptonshire, United Kingdom

Anthony J Salloway