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 ).