US 4,908,578 AGranted

Method of and device for generating interleaved multiple-slice multiple-echo pulse sequences for MRI

AssigneeU.S. Philips Corporation

InventorFilips Van Liere

Life of this patent

Estimating the term…

Loading patent…

Abstract

MRI utilizes so-called multiple-slice multiple-echo pulse sequences. Pulse sequences are generated in order to produce echo resonance signals in different sub-regions of a body, after which images of the various sub-regions are reconstructed from the resonance signals. The pulse sequences, for example spin echo sequences, are successively generated for the various sub-regions. More than one echo resonance signal can be generated by means of each pulse sequence. In order to reduce the overall measuring time the invention proposes the interleaving of a pulse sequence (ex1, ep11, er11, ep12, er12) for a sub-region with pulse sequences (ep02, er-12, ex2, ep21, er21, er02, ex3, ep31, er31, ep22) for other sub-regions. It is essential that the excitation pulse (ex1), the echo pulses (ep11, ep12) and the echo resonance signals (er11, er12) are phase coherent within a pulse sequence.

Claims16

Dependent claims

A method of determining a nuclear magnetization distribution from magnetic resonance signals which are generated in plural three-dimensional sub-regions in a body by the application, in the presence of a steady, uniform magnetic field, of cycles of respective plural sub-region-selective sequences of RF electromagnetic field pulses and magnetic field gradient waveforms, in three mutually orthogonal directions, superimposed on said steady, uniform magnetic field, which respective plural sub-region-selective sequences are all applied in each cycle, each sub-region-selective sequence comprising an RF excitation pulse in the presence of a selection gradient waveform associated with said sequence, for selection in a first direction, followed by a phase encoding gradient waveform, which is varied in amplitude, in a second and/or a third direction, from one cycle to the next for phase encoding, followed by one or more RF echo pulses which generate respective one or more echo resonance signals, wherein first and second of said plural sub-region-selective sequences are interleaved in time with each other in that the RF excitation pulse of the second sub-region-selective sequence occurs in the time interval between the RF excitation pulse and the last of said one or more echo resonance signals generated in the first sub-region-selective sequence and wherein within each sub-region-selective sequence said RF excitation pulse and said one or more RF echo pulses are phase coherent with each other.

A device for determining a nuclear magnetization distribution from magnetic resonance signals to be generated in plural three-dimensional sub-regions in a body comprising:

means for generating a steady, uniform magnetic field;
means for phase coherent generating of RF electromagnetic field pulses;
means for generating field gradient waveforms, in three mutually orthogonal directions, superimposed on said steady, uniform magnetic field;
control means for controlling the means for generating the steady uniform magnetic field and for controlling the means for generating field gradient waveforms to cause the application in cycles of respective plural sub-region-selective sequences of RF electromagnetic field pulses and magnetic field gradient waveforms, which respective plural sub-region-selective sequences are all applied in each cycle, each sub-region-selective sequence comprising an RF excitation pulse in the presence of a selection gradient waveform associated with said sequence, for selection in a first direction, followed by a phase encoding gradient waveform, which is varied in amplitude, in a second and/or a third direction, from one cycle to the next for phase encoding, followed by one or more RF echo pulses which generate respective one or more echo resonance signals, wherein first and second of said plural sub-region-selective sequences are interleaved in time with each other in that the RF excitation pulse of the second sub-region-selective sequence occurs in the time interval between the RF excitation pulse and the last of said one or more echo resonance signals generated in the first sub-region-selective sequence and wherein within each sub-region-selective sequence said RF excitation pulse and said one or more RF echo pulses are phase coherent with each other;
means for receiving, detecting and sampling the echo resonance signals;
and processing means which include programmed arithmetic means for determining the nuclear magnetization distribution from the sampled echo resonance signals.

3 more elements

Dependencies are inferred from the claim text.