# US 10,768,261 B2 · Alternating gradients for metal-induced artifacts correction in magnetic resonance imaging

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- Number: US 10,768,261 B2
- Document ID: US10768261B2
- Status: Granted
- Kind: B2
- Application number: 15/921,495
- Filed: 2018-03-14
- Published: 2018-09-20
- Granted: 2020-09-08
- Earliest claimed: 2017-03-15
- Assignees: The Board of Trustees of the Leland Stanford Junior University
- Applicants: The Board of Trustees of the Leland Stanford Junior University
- Inventors: Xinwei Shi; Brian A. Hargreaves
- Web page: https://patentgrep.com/patent/US10768261B2

## CPC

- G01R 33/56536: {due to magnetic susceptibility variations}
- G01R 33/5608: {Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels (image data processing or generation, in general G06T)}
- G06T 5/73: Deblurring; Sharpening
- G01R 33/4835: {of multiple slices}
- G06T 2207/10088: Magnetic resonance imaging [MRI]
- G06T 2207/20221: Image fusion; Image merging
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

A method for magnetic resonance imaging suppresses off-resonance gradient-induced image artifacts due to metal. The method includes performing by a magnetic resonance imaging (MRI) apparatus two multi-spectral imaging (MSI) acquisitions within a field of view of the MRI apparatus, where the two MSI acquisitions have alternating-sign readout gradients. The two MSI acquisitions are then processed and combined by the MRI apparatus using a weighted image combination to produce a final image.

## Claims

### Claim 1

A method for magnetic resonance imaging that suppresses off-resonance gradient-induced image artifacts due to metal, the method comprising:
performing by a magnetic resonance imaging (MRI) apparatus two multi-spectral imaging (MSI) acquisitions within a field of view of the MRI apparatus, where the two MSI acquisitions have alternating-sign readout gradients during signal readout; and
processing and combining by the MRI apparatus the two MSI acquisitions using a weighted image combination to produce a final image;
wherein combining the two MSI acquisitions using the weighted image combination comprises weighting a MSI acquisition m+ with weight w+, weighting a MSI acquisition m− with weight w−, where the weights w+ and w− include effects of both an RF excitation weight wRF and local gradient weight wG, and where MSI acquisition m+ and MSI acquisition m− have opposite directions of readout gradients.

### Claim 2 (depends on 1)

The method of claim 1 wherein the two MSI acquisitions have alternating-sign slice-select gradients and view-angle tilting gradients.

### Claim 3 (depends on 1)

The method of claim 1 wherein the RF excitation weight wRF and the local gradient weight wG are determined from a composite field map f.

### Claim 4 (depends on 3)

The method of claim 3 wherein the composite field map f is determined from MSI acquisition m+, MSI acquisition m−, and corresponding field maps f+ and f−.