Magnetic resonance apparatus having reduced "dead time"

Apparatus for reducing dead-time in a magnetic resonance apparatus comprising:

• an RF transmitter resonator for applying an RF excitation pulse;
• first and second RF receiver resonators arranged to surround a sample under investigation and located in mutually non-parallel directions, said first and second RF receiver resonators having substantially identical ringing characteristics, said first and second RF receiver resonators arranged to detect respective signals each containing a ringing component, in response to said RF excitation pulse;
• a 180 degree phase shifter for introducing a 180 degree shift between the signals detected by said first and second receiver resonators;
• a signal combiner for receiving said phase shifted signals and generating an output representing the difference between the detected RF signals, to provide an output free of said ringing component.

A method for eliminating a ringing component during a magnetic resonance investigation of an object comprising the steps of:

• applying a static magnetic field to the object;
• applying an RF excitation pulse to the object;
• detecting, via a first and a second RF receiver resonator surrounding said object and arranged to detect fields in mutually non-parallel directions, respective RF signals comprising a directional information component and a non-directional ringing component;
• and
• combining the RF signal detected by said first RF receiver resonator with that detected by said second resonator, in such a way as to provide a signal containing said directional information component but free of said non-directional ringing component.

Pulsed magnetic resonance apparatus comprising:

• means for applying a static magnetic field;
• an RF transmitter resonator for applying an RF excitation pulse to an object under investigation;
• first and second RF receiver resonators surrounding said object and arranged to detect first and second RF signals each containing a respective ringing component, in response to the RF excitation pulse;
• means to provide an output signal free of said ringing component, said output signal representing the difference between the signals received by said first and said second RF receiver resonators.

Pulsed magnetic resonance apparatus comprising:

• means for applying a static magnetic field;
• a single RF transmitter resonator for applying an RF excitation pulse to an object;
• first and second RF receiver resonators located in mutually non-parallel directions;
• and
• means to provide a signal representing the difference between the signals received by said first and said second RF receiver resonators in response to the RF excitation pulse, wherein each of the first and second RF receiver resonators is connected to a separate receiver channel, and a signal attenuator and/or a phase shifter is provided in at least one of the receiver channels to vary the relative amplitude and/or phase between the signals received by the two receiver resonators.