Magnetic resonance imaging apparatus
A magnetic resonance imaging apparatus of an embodiment includes: an imaging condition setting section configured to set an imaging condition for a main scan, a preparatory scan performing section configured to repeat a preparatory scan to be performed by the use of the imaging condition for a main scan and a changeably inputted center frequency so as to generate a preparatory image in real time, a display section on which the preparatory image can be displayed in real time, an optimum center frequency setting section configured to change the center frequency so as to change a situation in which a banding artifact appears and configured to set an optimum center frequency according to a user operation based on an observation of the preparatory image, and a main scan performing section configured to reconstruct an image for a diagnosis by using the optimum center frequency having been set.
1. A magnetic resonance imaging (MRI) apparatus comprising:
an MRI system including at least one processor configured to
set an imaging condition for a main scan to obtain a diagnostic image;
accept a user input center frequency changeably inputted in real time;
repeat a preparatory scan performed by use of the set imaging condition and the center frequency changeably inputted in real time and generate preparatory images in real time visibly depicting a banding artifact using the preparatory scan data acquired in the repeated preparatory scans;
display the preparatory images in real time;
change the center frequency according to a user operation via a user interface so as to change where the banding artifact appears, the optimum center frequency being set according to a user operation based on observation of the preparatory images; and
perform the main scan by using the set optimum center frequency and the set imaging condition for the main scan to reconstruct the diagnostic image.
2. The magnetic resonance imaging apparatus according to claim 1 , wherein both the main scan and the preparatory scan are performed using an SSFP (Steady State Free Precession) method.
3. The magnetic resonance imaging apparatus according to claim 1 , wherein
the imaging condition set for the main scan includes information on an imaging cross section image which is to be captured in the main scan, and
an imaging cross section which is same as a cross section to be used for the main scan is included in the preparatory scan.
4. The magnetic resonance imaging apparatus according to claim 3 , wherein, when the imaging cross section in the main scan includes a plurality of slices, a middle one of the slices is included in the preparatory scan, and when the imaging cross section in the main scan is a slab having a certain thickness, one slice corresponding to a middle position of the slab is included in the preparatory scan.
5. The magnetic resonance imaging apparatus according to claim 1 , wherein
the preparatory scan is automatically started according to a user operation to start the main scan after the imaging condition is set, and
the main scan is automatically started when the optimum center frequency is set according to a user operation during the repeated preparatory scans.
6. The magnetic resonance imaging apparatus according to claim 1 , wherein
the set imaging condition for a main scan includes information on resolution in the main scan, and
the preparatory scan is performed in such a way that resolution is rendered the same as the resolution in the main scan.
7. The magnetic resonance imaging apparatus according to claim 6 , wherein the preparatory scan acquires a signal only in a specific range centered at a phase encoding quantity of zero, and complements zero for a range excepting the specific range to perform reconstruction processing.
8. The magnetic resonance imaging apparatus according to claim 1 , wherein information on an imaging cross section in a main scan to be performed on the basis of an optimum center frequency having been previously set for acquisition of a prior diagnostic image is displayed on a user interface display.
9. The magnetic resonance imaging apparatus according to claim 1 , wherein the optimum center frequency is set so that the banding artifact is put apart from what is to be observed.
10. A magnetic resonance imaging (MRI) apparatus comprising:
an MRI system including at least one processor configured to
set an imaging condition for a main scan to obtain a diagnostic image;
repeat a preparatory scan performed by use of the set imaging condition, the preparatory scan generating preparatory images in real time visibly depicting a banding artifact using data acquired in the preparatory scans;
display the preparatory images in real time;
accept a user input shift value of a center frequency that a user has determined based on the banding artifact appearing on the displayed preparatory images;
add and/or subtract the user-inputted shift value of the center frequency to and/or from a center frequency corresponding to that used for generating the preparatory images used for determination of the shift value of the center frequency so as to obtain a new center frequency, the optimum center frequency being set to the new obtained center frequency; and
perform the main scan using the set optimum center frequency and the imaging condition for the set main scan so as to reconstruct the diagnostic image.
11. The magnetic resonance imaging apparatus according to claim 10 , wherein
the imaging condition for the main scan includes a repetition period of time (TR) for an excitation pulse sequence, and
the preparatory scan is performed with a repetition period of time (2TR) twice as long as the set repetition period of time.