System and method for an eddy-current field compensation in magnetic resonance imaging
A system and method for acquiring a calibrated eddy-current field model in magnetic resonance imaging (MRI) are provided. The method may include one or more of the following operations. An eddy-current field model may be obtained. The eddy-current field model may transformed by Laplace Transformation. Data of an eddy-current field may be obtained. The data of the eddy-current field may be processed. A calibrated eddy-current field model may be acquired. In addition, the calibrated eddy-current field model may be used to compensate an eddy-current field.
1. A method for calibrating an eddy-current, the method comprising:
establishing an eddy-current field model, wherein the eddy-current field is expressed by Laplace transformation;
obtaining data of a first eddy-current field and using the established eddy-current field model to process the data of the first eddy-current field to obtain a first parameter;
fitting the established eddy-current field model with the data of the first eddy-current field and the first parameter to acquire a second parameter;
incorporating the second parameter into the established eddy-current field model to obtain a calibrated eddy-current field model; and
calibrating the eddy-current based on the calibrated eddy-current field model.
2. The method of claim 1 , wherein the processing the data of the first eddy-current field comprises:
performing inverse Laplace transformation (ILT) based on the data of the first eddy-current field to obtain a Laplacian spectrum;
acquiring information of a peak of the Laplacian spectrum; and
determining the first parameter based on the information of the peak.
3. The method of claim 2 , wherein the Laplacian spectrum comprises a sparse Laplacian spectrum or a smooth Laplacian spectrum.
4. The method of claim 2 , comprising:
obtaining a first threshold;
comparing the absolute value of an intensity of the peak with the first threshold; and
marking, if the absolute value of the intensity of the peak exceeds the first threshold, the peak as a reliable spectrum peak.
5. The method of claim 2 , wherein the peak comprises a reliable spectrum peak.
6. The method of claim 5 , wherein the first parameter is based on a parameter of the reliable spectrum peak.
7. The method of claim 5 , wherein the determining the first parameter comprises:
determining a boundary of the reliable spectrum peak;
calculating a total intensity of the reliable spectrum peak within the boundary; and
setting the first parameter based on the total intensity of the reliable spectrum peak.
8. The method of claim 1 , wherein the processing the data of the eddy-current field comprises:
applying regularization to calculate the data of the eddy-current field based on inverse Laplace transformation (ILT).
9. The method of claim 1 , wherein the acquiring a second parameter comprising applying a nonlinear least square fitting.
10. The method of claim 1 further comprising:
identifying at least one characteristic component of the first eddy-current field based on the calibrated eddy-current field model; and
compensating the first eddy-current field based on the at least one characteristic component of the first eddy-current field.
11. The method of claim 1 further comprising:
identifying a plurality of characteristic components of the eddy-current field based on the calibrated eddy-current field model; and
compensating the first eddy-current field based on the plurality of characteristic components.
12. The method of claim 11 further comprising:
obtaining a second eddy-current field comprising the plurality of characteristic components; and
compensating the second eddy-current field based on the plurality of characteristic components.
13. A non-transitory computer-readable storage medium storing a computer program having instructions, the instructions, when executed by the processor, causing the processor to perform operations comprising:
establishing an eddy-current field model, wherein the eddy-current field is expressed by Laplace transformation;
obtaining data of an eddy-current field using the established eddy-current field model to process the data of the eddy-current field to obtain a first parameter;
fitting the established eddy-current field model with the data of the first eddy-current field and the first parameter to acquire a second parameter;
incorporating the second parameter into the established eddy-current field model to obtain a calibrated eddy-current field mode; and
calibrating the eddy-current based on the calibrated eddy-current field model.
14. The non-transitory computer-readable storage medium of claim 13 ,
wherein the acquiring a second parameter comprising applying a nonlinear least square fitting.
15. The non-transitory computer-readable storage medium of claim 13 , wherein the processing the data of the eddy-current field comprises:
applying regularization to calculate the data of the eddy-current field based on inverse Laplace transformation (ILT).
16. A magnetic resonance imaging (MRI) system comprising:
a processor; and;
instructions that, when executed by the processor, cause the processor to perform operations comprising:
establishing an eddy-current field model, wherein the eddy-current field is expressed by Laplace transformation;
obtaining data of a first eddy-current field of an MRI scanner and using the established eddy-current field model to process the data of the first eddy-current field to obtain a first parameter;
fitting the established eddy-current field model with the data of the first eddy-current field and the first parameter to acquire a second parameter; and
incorporating the second parameter into the established eddy-current field model to obtain a calibrated eddy-current field model.
17. The MRI system of claim 16 , wherein the processing the data of the first eddy-current field based on the eddy-current field model to obtain a first parameter comprises:
performing inverse Laplace transformation (ILT) based on the data of the first eddy-current field to obtain a Laplacian spectrum;
acquiring information of a peak of the Laplacian spectrum; and
determining the first parameter based on the information of the peak.
18. The MRI system of claim 16 , the operations further comprising:
identifying at least one characteristic component of the first eddy-current field based on the calibrated eddy-current field model; and
compensating the first eddy-current field based on the at least one characteristic component of the first eddy-current field.
19. The MRI system of claim 16 , the operations further comprising:
identifying a plurality of characteristic components of the eddy-current field based on the calibrated eddy-current field model; and
compensating the first eddy-current field based on the plurality of characteristic components.
20. The MRI system of claim 19 , the operations further comprising:
obtaining a second eddy-current field comprising the plurality of characteristic components; and
compensating the second eddy-current field based on the plurality of characteristic components.