MRI Motion Correction via 3D Navigator Mapping
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Solution Overview
Problem
Current MRI systems face challenges in accurately correcting for through-plane motion during multi-slice acquisitions, leading to image artifacts and reduced image quality, as existing motion compensation methods are limited to in-plane corrections and lack quantitative correction for through-plane motion.
Innovation Solution
A method that involves acquiring and reconstructing three-dimensional navigator data from central k-space data to determine a mapping between initial and subsequent navigator data, allowing for prospective correction of slice group acquisitions by adjusting gradient fields and scan parameters, thereby addressing both in-plane and through-plane rigid body motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing motion compensation methods are used, then in-plane motion correction is achieved, but through-plane motion correction is not achieved leading to image artifacts
Solution Approach 1:
The patent extends motion correction from 2D in-plane to 3D by incorporating through-plane motion measurement. Navigator echoes are used to track motion in the slice direction (through-plane), adding a third dimension to the correction capability. This allows the system to measure and correct motion components that were previously unmeasured, eliminating artifacts caused by through-plane motion while maintaining in-plane correction.
2Measurement precision
If additional navigators are added to measure through-plane motion, then motion correction capability is improved, but scan time and complexity increase
Solution Approach 1:
The patent combines through-plane motion measurement with the existing imaging sequence by incorporating navigator echoes into the standard multi-slice acquisition. Instead of adding separate navigator acquisitions, the method integrates motion measurement into the imaging process itself, using the same RF pulses and gradient fields to acquire both imaging data and motion information simultaneously.
Solution Approach 2:
The imaging sequence is designed to serve multiple functions: acquiring diagnostic image data and measuring through-plane motion. The navigator echoes are embedded within the imaging sequence, allowing the same system components and time resources to perform dual functions of imaging and motion tracking without requiring additional dedicated navigator acquisitions.
3Productivity
If multi-slice acquisition is performed, then imaging efficiency is improved, but through-plane motion correction becomes difficult
Solution Approach 1:
The patent divides the motion correction task into manageable components: in-plane motion correction using existing methods and through-plane motion correction using navigator echoes. Each slice group is processed independently with its own motion parameters measured and applied, allowing the complex multi-slice motion correction to be broken down into simpler, independent correction steps that can be implemented efficiently.
Data Source
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AI summary
The invention provides for a magnetic resonance imaging system (100) for acquiring magnetic resonance data (142, 148, 158) with a pulse sequence (140) for multiple slice acquisition performed over multiple repetition cycles. The magnetic resonance imaging system further comprises a processor (540) for controlling the magnetic resonance imaging system. The execution of the instructions cause the processor to: acquire (200) a first slice group (142) of the magnetic resonance data during a first repetition cycle; extract (202) first central k-space data (144) from the first slice group; reconstruct (204) first navigator data (146) using the first central k-space data. Execution of the instructions causes the processor to repeatedly: acquire (206) a subsequent slice group (148) of the magnetic resonance data during a subsequent repetition cycle; extract (208) subsequent central k-space data (150) from the subsequent slice group; reconstruct (210) subsequent navigator data (152) using the subsequent central k-space data; determining (212) a mapping (154) from the first navigator data to the subsequent navigator data; and correct (214) the acquisition of a next slice group of the magnetic resonance data using the mapping.