US 5,438,263 A · Method of selectable resolution magnetic resonance imaging

Abstract

Multi-slice selectable resolution NMR data acquisition in which multiple slice regions in an object are defined, and the slice regions are excited to emit NMR signals. The NMR signals are spatially encoded, and at least two selected slice regions are excited to emit NMR signals encoded with different spatial resolutions.

Claims16

Dependent claims

A method of obtaining nuclear magnetic resonance (NMR) data for multiple slice regions within an object with different spatial resolutions during a single scan of the object, comprising:

defining a plurality of slice regions in an object for which NMR data is to be obtained;
exciting emission of spatially encoded NNR signals from the slice regions, wherein at least two selected slice regions are excited to emit NMR signals encoded with different spatial resolutions;
receiving the emitted NMR signals;
and
repeating the excitation of the slice regions without interruption until NMR signals from each slice region sufficient to obtain the desired resolution have been received.

2 more elements

A method of obtaining magnetic resonance imaging data in multiple slices with different resolutions during a single scan of an object, comprising:

positioning an object to be imaged within a magnetic field;
establishing a magnetic field gradient within the magnetic field that is effective to define slice regions within the object that each contain nuclei which exhibit a respective distinct NNR frequency corresponding to the slice region;
irradiating the object with radio frequency energy to resonate nuclei of the object within a selected first slice region;
establishing magnetic field gradients to spatially encode the NNR signals emitted from the nuclei within the first slice region;
receiving the NMR signals emitted from nuclei within the first slice region;
irradiating the object with radio frequency energy to resonate nuclei of the object within a selected second slice region;
establishing magnetic field gradients to spatially encode the NMR signals emitted from the nuclei within the second slice region;
setting the magnetic field gradient effective to define slice regions and the magnetic field gradients for spatially encoding the NMR signals emitted from the second slice region with a spatial resolution different from that of the first slice region;
receiving the NMR signals emitted from the nuclei within the second slice region, and
repeating the steps of irradiating the object, establishing magnetic field gradients and receiving NMR signals for each slice region to be imaged until data from all of the slice regions to be imaged has been collected.

7 more elements

A method of obtaining magnetic resonance imaging (MRI) data for multiple planes within an object with different resolutions during a single scan of the object, comprising:

positioning an object within a magnetic field;
determining first and second selected planes in the object for which MRI data is to be obtained,
subjecting the object to a plurality of repetitions of a first repetition sequence composed of nuclear magnetic resonance (NMR) excitation and magnetic field gradient pulses, each of said repetitions of said first repetition sequence including the steps of applying an excitation pulse, applying magnetic gradient fields for spatially encoding the nuclear spins excited by said excitation pulse and reading out of an NMR signal produced by said excitation pulse, said excitation pulse for said first repetition sequence being applied at a predetermined frequency in the presence of a predetermined slice selector magnetic field gradient for defining an excited slice region within said object corresponding to said first selected plane, and said plurality of repetitions of said first repetition sequence being carried out in a manner to encode spatial information into a first collection of NMR signals representative of MRI data for said first selected plane with a first spatial resolution;
subjecting the object to a plurality of repetitions of a second repetition sequence composed of NMR excitation and magnetic field gradient pulses, each of said repetitions of said second repetition sequence including the steps of applying an excitation pulse, applying magnetic gradient fields for spatially encoding the nuclear spins excited by said excitation pulse, and reading out of an NMR signal produced by said excitation pulse, said excitation pulse for said second repetition sequence being applied at a predetermined frequency in the presence of a predetermined slice selector magnetic field gradient for defining an excited slice region within said object corresponding to said second selected plane, and said plurality of repetitions of said second repetition sequence being carried out in a manner to encode spatial information into a second collection of NMR signals representative of MRI data for said second selected plane with a second spatial resolution different from that for said first selected plane;
and
said plurality of repetitions of said first and second repetition sequences each being carried out during the course of a single scan of said object and each being continued approximately throughout said single scan, the repetition time interval for repeating each of said first and second repetition sequences being substantially the same, and said steps of applying an excitation pulse and reading out of an NMR signal for each repetition of said second repetition sequence being performed at a different time during said repetition time interval than each of said steps of applying an excitation pulse and reading out of an NMR signal for said first repetition sequence.

3 more elements

Dependencies are inferred from the claim text.

Abstract

Claims16

Dependent claims

A method of obtaining nuclear magnetic resonance (NMR) data for multiple slice regions within an object with different spatial resolutions during a single scan of the object, comprising:

defining a plurality of slice regions in an object for which NMR data is to be obtained;
exciting emission of spatially encoded NNR signals from the slice regions, wherein at least two selected slice regions are excited to emit NMR signals encoded with different spatial resolutions;
receiving the emitted NMR signals;
and
repeating the excitation of the slice regions without interruption until NMR signals from each slice region sufficient to obtain the desired resolution have been received.

2 more elements

A method of obtaining magnetic resonance imaging data in multiple slices with different resolutions during a single scan of an object, comprising:

positioning an object to be imaged within a magnetic field;
establishing a magnetic field gradient within the magnetic field that is effective to define slice regions within the object that each contain nuclei which exhibit a respective distinct NNR frequency corresponding to the slice region;
irradiating the object with radio frequency energy to resonate nuclei of the object within a selected first slice region;
establishing magnetic field gradients to spatially encode the NNR signals emitted from the nuclei within the first slice region;
receiving the NMR signals emitted from nuclei within the first slice region;
irradiating the object with radio frequency energy to resonate nuclei of the object within a selected second slice region;
establishing magnetic field gradients to spatially encode the NMR signals emitted from the nuclei within the second slice region;
setting the magnetic field gradient effective to define slice regions and the magnetic field gradients for spatially encoding the NMR signals emitted from the second slice region with a spatial resolution different from that of the first slice region;
receiving the NMR signals emitted from the nuclei within the second slice region, and
repeating the steps of irradiating the object, establishing magnetic field gradients and receiving NMR signals for each slice region to be imaged until data from all of the slice regions to be imaged has been collected.

7 more elements

A method of obtaining magnetic resonance imaging (MRI) data for multiple planes within an object with different resolutions during a single scan of the object, comprising:

positioning an object within a magnetic field;
determining first and second selected planes in the object for which MRI data is to be obtained,
subjecting the object to a plurality of repetitions of a first repetition sequence composed of nuclear magnetic resonance (NMR) excitation and magnetic field gradient pulses, each of said repetitions of said first repetition sequence including the steps of applying an excitation pulse, applying magnetic gradient fields for spatially encoding the nuclear spins excited by said excitation pulse and reading out of an NMR signal produced by said excitation pulse, said excitation pulse for said first repetition sequence being applied at a predetermined frequency in the presence of a predetermined slice selector magnetic field gradient for defining an excited slice region within said object corresponding to said first selected plane, and said plurality of repetitions of said first repetition sequence being carried out in a manner to encode spatial information into a first collection of NMR signals representative of MRI data for said first selected plane with a first spatial resolution;
subjecting the object to a plurality of repetitions of a second repetition sequence composed of NMR excitation and magnetic field gradient pulses, each of said repetitions of said second repetition sequence including the steps of applying an excitation pulse, applying magnetic gradient fields for spatially encoding the nuclear spins excited by said excitation pulse, and reading out of an NMR signal produced by said excitation pulse, said excitation pulse for said second repetition sequence being applied at a predetermined frequency in the presence of a predetermined slice selector magnetic field gradient for defining an excited slice region within said object corresponding to said second selected plane, and said plurality of repetitions of said second repetition sequence being carried out in a manner to encode spatial information into a second collection of NMR signals representative of MRI data for said second selected plane with a second spatial resolution different from that for said first selected plane;
and
said plurality of repetitions of said first and second repetition sequences each being carried out during the course of a single scan of said object and each being continued approximately throughout said single scan, the repetition time interval for repeating each of said first and second repetition sequences being substantially the same, and said steps of applying an excitation pulse and reading out of an NMR signal for each repetition of said second repetition sequence being performed at a different time during said repetition time interval than each of said steps of applying an excitation pulse and reading out of an NMR signal for said first repetition sequence.

3 more elements

Dependencies are inferred from the claim text.

Method of selectable resolution magnetic resonance imaging

Life of this patent

Abstract

Claims16

Method of selectable resolution magnetic resonance imaging

Life of this patent

Abstract

Claims16