System of Electric Coils for Transmitting and Receiving Radio-Frequency Magnetic Fileds in a Magnetic-Resonance Imaging Apparatus, and Magnetic-Resonance Imaging Apparatus Provided with Such a System of Electric Coils

摘要

The invention relates to a magnetic resonance imaging (MRI) apparatus comprising an electrical coil system (17) for transmitting and receiving a radio-frequent (RF) magnetic field from an examination volume (3) of the MRI apparatus. The electrical coil system (17) comprises at least one surface coil (35) which substantially extends in a plane. The surface coil serves for transmitting and/or receiving an RF magnetic field which is substantially oriented perpendicular to the plane of the surface coil (35). The surface coil (35) has a main coil axis (37). When the MRI apparatus is in use the main coil axis (37) extends substantially parallel to a main magnetic field in the examination volume (3) of the MRI apparatus. On both sides of the main coil axis (37) the surface coil (35) comprises an electrically conducting element (39) which extends substantially parallel to the main coil axis (37). To provide a surface coil (35) which transmits more homogeneous RF magnetic fields and/or has a more homogeneous sensitivity for received RF magnetic fields than known surface coils, at least one of the electrically conducting elements (39) of the surface coil (35) comprises at least two electrical conductors (41). With respect to their distance to the main coil axis (37) these electrical conductors (41) are positioned at a relatively short distance from each other. In the plane of the surface coil (35) the electrical conductors (41) substantially extend parallel to the main coil axis (37) of the surface coil (35).