Optimization of specific absorption rate performance
View Patent ↗The embodiments relate to devices and methods for MRT imaging with a MRT, where a patient table having the scan subject is moved in at least one direction along at least one displacement path, determination of a quantity representing the SAR effect on the scan subject being carried out at a plurality of positions along the displacement path, a suitable position of the patient table, lying on a displacement path, being determined, at which the MRT imaging of the scan subject imaging region, to be scanned, of the scan subject is subsequently intended to be carried out.
1. A method for magnetic resonance tomograph imaging with a magnetic resonance tomograph, the method comprising:
moving, using a controller, a patient table having a scan subject in at least one direction along at least one displacement path;
determining a quantity representing a radio frequency (RF) influence on the scan subject at a plurality of positions along the at least one displacement path; and
determining, as a function of the quantity, a first position of the patient table lying on the at least one displacement path at which the magnetic resonance tomograph imaging of an imaging region is to be scanned.
2. The method as claimed in claim 1 , wherein the patient table is moved along only one displacement path or in only one direction in order to determine the first position.
3. The method as claimed in claim 1 , wherein the patient table is moved along more than one displacement path or in more than one direction in order to determine at least one first position.
4. The method as claimed in claim 1 , wherein the patient table is moved is a direction in which the scan subject is introduced into a field of view of the magnetic resonance tomograph.
5. The method as claimed in claim 1 , wherein one or two of the directions in which the patient table is moved is or are orthogonal to a direction in which the scan subject is introduced into a field of view of the magnetic resonance tomograph.
6. The method as claimed in claim 1 , wherein the displacement path is less than twenty centimeters long.
7. The method as claimed in claim 1 , wherein the first position of the patient table is relative to a midpoint of a field of view of the magnetic resonance tomograph or relative to at least one RF transmission coil of the magnetic resonance tomograph.
8. The method as claimed in claim 1 , wherein the first position lies outside a midpoint of a field of view of the magnetic resonance tomograph.
9. The method as claimed in claim 1 , wherein the first position lies in such a way that a part of the imaging region lies outside a field of view of the magnetic resonance tomograph.
10. The method as claimed in claim 1 , wherein the first position is determined only from positions of the plurality of positions that lie within a predetermined or stored spatial tolerance range with respect to the first position, wherein the stored spatial tolerance range is a maximum distance of the first position from a midpoint of a field of view.
11. The method as claimed in claim 10 , wherein the stored spatial tolerance range is less than 10 centimeters.
12. The method as claimed in claim 1 , wherein by a tolerance range respectively stored in the magnetic resonance tomograph for one or more measurement protocols, a maximum distance as a position offset of a suitable position from a midpoint of a field of view is taken into account during the determination of the first position from the plurality of positions.
13. The method as claimed in claim 1 , wherein the first position of the patient table is a position at which there is a local or global minimum of the quantity representing the RF influence on the scan subject.
14. The method as claimed in claim 1 , wherein the quantity representing the RF influence on the scan subject is a measured specific absorption rate (SAR) or a SAR calculated with a model.
15. The method as claimed in claim 1 , wherein the first position of the patient table is determined before the magnetic resonance tomograph imaging with the magnetic resonance tomograph, at which a drive amplitude or power for a RF amplifier of the magnetic resonance tomograph, used for a desired flip angle, a desired RF pulse shape during the magnetic resonance tomograph imaging, or a SAR/BF ratio, is minimized.
16. The method as claimed in claim 1 , wherein during the displacement of the patient table along a displacement path, a drive amplitude or power of a RF amplifier of the magnetic resonance tomograph, used for a desired flip angle during the magnetic resonance tomograph imaging or a SAR/BF ratio, is determined at the plurality of positions.
17. The method as claimed in claim 1 , wherein in order to determine the quantity representing the RF influence on the scan subject, determined values are stored as a function of the position of the plurality of positions at which the determined values were determined.
18. The method as claimed in claim 1 , further comprising generating a magnetic resonance tomograph image, wherein a position offset between the first position and a midpoint of a field of view of the magnetic resonance tomograph is taken into account when generating the magnetic resonance tomograph image.
19. A non-transitory computer-readable storage medium having stored therein a computer program for controlling a target system when executed by a computer, the storage medium comprising instructions for:
moving a patient table having a scan subject in at least one direction along at least one displacement path;
determining a quantity representing a radio frequency (RF) influence on the scan subject at a plurality of positions along the at least one displacement path; and
determining, as a function of the quantity, a first position of the patient table lying on the at least one displacement path at which a magnetic resonance tomograph imaging of an imaging region is to be scanned.