Method for estimating systematic imperfections in medical imaging systems with deep learning
A method for magnetic resonance imaging (MRI) includes steps of acquiring by an MRI scanner undersampled magnetic-field-gradient-encoded k-space data; performing a self-calibration of a magnetic-field-gradient-encoding point-spread function using a first neural network to estimate systematic waveform errors from the k-space data, and computing the magnetic-field-gradient-encoding point-spread function from the systematic waveform errors; reconstructing an image using a second neural network from the magnetic-field-gradient-encoding point-spread function and the k-space data.
1. A method for magnetic resonance imaging (MRI) comprising:
acquiring by an MRI scanner undersampled magnetic-field-gradient-encoded k-space data;
performing a self-calibration of a magnetic-field-gradient-encoding point-spread function using a first neural network to estimate systematic waveform errors from the k-space data, and computing the magnetic-field-gradient-encoding point-spread function from the systematic waveform errors;
reconstructing an image using a second neural network from the magnetic-field-gradient-encoding point-spread function and the k-space data.
2. The method of claim 1 wherein the magnetic-field-gradient-encoded k-space data is wave-encoded k-space data.
3. The method of claim 1 wherein the magnetic-field-gradient-encoding point-spread function is a wave-encoding point-spread function.
4. The method of claim 1 wherein acquiring the undersampled magnetic-field-gradient-encoded k-space data comprises using a magnetic-field-gradient-encoded single shot fast spin echo sequence with variable density sampling.
5. The method of claim 1 wherein the systematic waveform errors comprise calibrated gradient time delay and isocenter location shift of magnetic-field-gradient-encoding gradients.
6. The method of claim 5 wherein the systematic waveform errors further comprise a scaling factor defining a ratio of actual and theoretical magnetic-field-gradient-encoding gradient amplitudes.
7. The method of claim 1 wherein performing a self-calibration of the magnetic-field-gradient-encoding point-spread function comprises using the first neural network to estimate systematic waveform errors from the k-space data, a theoretical maximum magnetic-field-gradient-encoding gradient amplitude, and a theoretical isocenter location.
8. The method of claim 1 wherein the second neural network used for reconstructing the image comprises multiple steps, wherein each step comprises a gradient update and a proximal step with a learned regularization network operator with trained parameters.