Magnetic resonance imaging apparatus, magnetic resonance imaging method, and non-transitory computer readable medium
According to one embodiment, a magnetic resonance imaging apparatus includes processing circuitry. The processing circuitry is configured to design a pulse sequence including a plurality of refocus pulses and a plurality of crusher gradient fields, in such a manner that a first crusher gradient field to be applied after a first refocus pulse group and a second crusher gradient field to be applied before a second refocus pulse group after the first refocus pulse group overlap one another at least partially. The processing circuitry is configured to acquire magnetic resonance spectroscopic signals by executing the designed pulse sequence.
1 . A magnetic resonance imaging apparatus, comprising:
processing circuitry configured to:
design a pulse sequence including a plurality of refocus pulses and a plurality of crusher gradient fields, in such a manner that a first crusher gradient field and a second crusher gradient field, each to be applied between adjacent refocus pulses of the plurality of refocus pulses, are combined into one; and
acquire magnetic resonance spectroscopic signals by executing the designed pulse sequence,
wherein the pulse sequence includes six refocus pulses.
2 . The magnetic resonance imaging apparatus according to claim 1 , wherein
a second refocus pulse and a fourth refocus pulse are included in the six refocus pulses,
a third refocus pulse and a fifth refocus pulse are included in the six refocus pulses, and
a time interval between the second refocus pulse and the third refocus pulse and a time interval between the fourth refocus pulse and the fifth refocus pulse are each shorter than a time interval between other refocus pulses.
3 . The magnetic resonance imaging apparatus according to claim 2 , wherein the processing circuitry is further configured to continuously apply, as the first crusher gradient field and the second crusher gradient field combined into one, a region selective gradient field regarding the second refocus pulse and the third refocus pulse, for the time interval between the second refocus pulse and the third refocus pulse.
4 . The magnetic resonance imaging apparatus according to claim 2 , wherein the processing circuitry is further configured to continuously apply, as the first crusher gradient field and the second crusher gradient field combined into one, a region selective gradient field regarding the fourth refocus pulse and the fifth refocus pulse, for the time interval between the fourth refocus pulse and the fifth refocus pulse.
5 . The magnetic resonance imaging apparatus according to claim 2 , wherein the processing circuitry is further configured to design a time interval between the second refocus pulse and the third refocus pulse and a time interval between the fourth refocus pulse and the fifth refocus pulse to be longer as a required crusher intensity increases.
6 . The magnetic resonance imaging apparatus according to claim 2 , wherein the processing circuitry is further configured to design a time interval between the second refocus pulse and the third refocus pulse and a time interval between the fourth refocus pulse and the fifth refocus pulse to be longer as a size of a volume of interest (VOI) in an axial direction increases.
7 . The magnetic resonance imaging apparatus according to claim 1 , wherein the processing circuitry is further configured to apply a MEGA pulse between a third refocus pulse and a fourth refocus pulse, and apply the MEGA pulse after a sixth refocus pulse, the MEGA pulse being a frequency selection pulse, the third refocus pulse, the fourth refocus pulse, and the sixth refocus pulse being included in the six refocus pulses.
8 . The magnetic resonance imaging apparatus according to claim 1 , wherein each of the six refocus pulses is designed to have a pulse length from 2.6 milliseconds to 3.4 milliseconds and have a pulse band from 2 kHz to 5 kHz.
9 . A magnetic resonance imaging comprising:
processing circuitry configured to:
design a pulse sequence including a plurality of refocus pulses and a plurality of crusher gradient fields, in such a manner that a first crusher gradient field and a second crusher gradient field, each to be applied between adjacent refocus pulses of the plurality of refocus pulses, are combined into one; and
acquire magnetic resonance spectroscopic signals by executing the designed pulse sequence,
wherein the pulse sequence is a localization by adiabatic selective refocusing (LASER) pulse sequence.
10 . The magnetic resonance imaging apparatus according to claim 9 , wherein the processing circuitry is further configured to adjust a time interval between refocus pulses in the LASER pulse sequence and the first and second crusher gradient fields according to a size of a volume of interest (VOI).
11 . A magnetic resonance imaging method, comprising:
designing a pulse sequence including a plurality of refocus pulses and a plurality of crusher gradient fields, in such a manner that a first crusher gradient field and a second crusher gradient field, each to be applied between adjacent refocus pulses of the plurality of refocus pulses, are combined into one; and
acquiring magnetic resonance spectroscopic signals by executing the designed pulse sequence,
wherein the pulse sequence includes six refocus pulses.
12 . A non-transitory computer readable medium including computer executable instructions, wherein the instructions, when executed by a processor, cause the processor to perform a method comprising:
designing a pulse sequence including a plurality of refocus pulses and a plurality of crusher gradient fields, in such a manner that a first crusher gradient field to be applied after a first refocus pulse group and a second crusher gradient field and a second crusher gradient field, each to be applied between adjacent refocus pulses of the plurality of refocus pulses, are combined into one; and
acquiring magnetic resonance spectroscopic signals by executing the designed pulse sequence using a magnetic resonance imaging apparatus,
wherein the pulse sequence includes six refocus pulses.