Magnetic resonance imaging device
View Patent ↗An object of the present invention is to provide a measuring technique which allows in the MRS measurement to suppress with a high degree of precision, incorporation of a signal of unwanted compounds which hinders measurement of a measurement object signal, independent of an imaging object region and the measurement object signal, thereby obtaining a stable and favorable signal spectrum. In the MRS measuring sequence, a spectrum selective inversion RF pulse, having a narrow band characteristic for selectively inverting only a signal peak of a compounds to be suppressed, and phase dispersion-refocusing GC pulses are applied at least one of before and after a region selective RF pulse. This MRS measuring sequence is repeated while changing the echo time TE at predetermined intervals, and nuclear magnetic resonance signals being obtained by the repetition are integrated. The amount of the spectrum selective inversion RF pulse to be applied may be changed according to the echo time TE.
1. A magnetic resonance imaging device, comprising a magnetic field generation unit to generate a static magnetic field, a radio frequency magnetic field, and a gradient magnetic field, a detection unit to detect a nuclear magnetic resonance signal generated from a subject placed in the static magnetic field, a computing unit to create a magnetic resonance spectrum from the nuclear magnetic resonance signal and displaying the magnetic resonance spectrum on a display unit, and a measurement control unit to control operations of the magnetic field generation unit, the detection unit, and the computing unit, and executing spectrum measurement for collecting the nuclear magnetic resonance signals which allow the magnetic resonance spectrum to be created,
the measurement control unit comprising,
a region selection unit to apply at least one pair of a region selective inversion radio frequency magnetic field and a slice selective gradient magnetic field, selectively inverting nuclear magnetization included only in a predetermined region, while repeating the spectrum measurement for a predetermined number of times, with changing the echo time at predetermined shift intervals, and
a suppression unit to apply a spectrum selective inversion radio frequency magnetic field for selectively inverting only the nuclear magnetization included in a predetermined compounds, at least one of before and after applying the region selective inversion radio frequency magnetic field and the slice selective gradient magnetic field, and simultaneously applying a phase dispersion gradient magnetic field and a phase refocusing gradient magnetic field, being identical in the magnitude of application amount and different in application polarity, before and after the spectrum selective inversion radio frequency magnetic field, respectively.
2. The magnetic resonance imaging device according to claim 1 , wherein,
the measurement control unit changes a period of time for applying the spectrum selective inversion radio frequency magnetic field, according to a length of the echo time of the spectrum measurement which applies the spectrum selective inversion radio frequency magnetic field.
3. The magnetic resonance imaging device according to claim 2 , wherein,
the measurement control unit sets a lower limit of a variable range of the echo time to be at least 90 ms.
4. The magnetic resonance imaging device according to claim 1 , wherein,
the measurement control unit sets a lower limit of a variable range of the echo time to be at least 90 ms.
5. The magnetic resonance imaging device according to claim 1 , wherein,
the measurement control unit comprises a user interface which allows a user to set at least one of the followings; the number of applications of the spectrum selective inversion radio frequency magnetic field, the shift interval, and the number of times of changing the echo time of the spectrum measurement.