MRI Multi-Slice Navigator Echoes for Motion-Corrected Imaging
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Solution Overview
Problem
Magnetic resonance imaging (MRI) is compromised by subject movement during imaging, leading to blurred images or ghost artifacts, particularly in functional MRI (fMRI) of the brain, due to the need for separate acquisition of navigator signals, which disrupts the desired signal-to-noise ratio and contrast.
Innovation Solution
A magnetic resonance imaging apparatus designs a first pulse sequence for simultaneous multi-slice excitation that includes both target slices and a navigator echo, allowing simultaneous acquisition of echo signals from both, followed by motion correction and reconstruction to improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If navigator signals are acquired separately from intended imaging, then movement correction can be performed, but the signal-to-noise ratio and contrast are degraded due to disrupted timing simultaneity
Solution Approach 1:
The patent combines the acquisition of navigator signals and intended imaging signals into a single pulse sequence execution. The processing circuitry designs a pulse sequence that simultaneously excites both the slice for navigator echo and the target slices, allowing both signal types to be acquired at the same timing without alternating between them, thus maintaining signal-to-noise ratio while enabling movement correction
Solution Approach 2:
The pulse sequence is designed to serve multiple functions simultaneously: it performs both intended imaging and navigator signal acquisition in a single execution. The processing circuitry configures the pulse sequence to excite both navigator slice and target slices, making the imaging system multi-functional without requiring separate dedicated sequences
2Reliability
If navigator signals are acquired separately from intended imaging, then movement information can be obtained, but imaging time is increased due to alternating acquisition requirements
Solution Approach 1:
The patent merges the acquisition of navigator signals and intended imaging signals into a single pulse sequence execution. The processing circuitry designs a pulse sequence that simultaneously excites both the slice for navigator echo and the target slices, allowing both signal types to be acquired at the same timing without alternating between them, thus maintaining signal-to-noise ratio while enabling movement correction
Solution Approach 2:
The pulse sequence enables continuous and simultaneous acquisition of both navigator and imaging signals without interruption or alternation. The processing circuitry ensures that both slice types are excited within the same pulse sequence cycle, maintaining continuous useful action throughout the imaging process without time loss
3Measurement precision
If a pulse sequence is designed under tuned conditions for desired SNR or contrast, then imaging quality is optimized, but flexibility to acquire additional navigator signals is reduced
Solution Approach 1:
The pulse sequence is designed to serve multiple functions simultaneously: it performs both intended imaging and navigator signal acquisition in a single execution. The processing circuitry configures the pulse sequence to excite both navigator slice and target slices, making the imaging system multi-functional without requiring separate dedicated sequences
Solution Approach 2:
The patent segments the excitation into different spatial regions (navigator slice and target slices) within a unified pulse sequence. The processing circuitry designs the pulse sequence to selectively excite specific slices for different purposes while maintaining overall sequence coherence, allowing both imaging and navigation functions to coexist
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the impact of subject movement by enabling simultaneous acquisition of navigator echoes with target slices, thereby improving image quality and reducing imaging time while maintaining desired signal characteristics.
Implementation Method 1
magnetic resonance imaging apparatus... simultaneously exciting the first slice group and the slice for the navigator echo... acquire an echo signal
Data Source
AI summary
According to one embodiment, a magnetic resonance imaging apparatus includes processing circuitry. The processing circuitry designs a first pulse sequence for a slice position relating to a first slice group and a slice for a navigator echo, the first slice group including a plurality of slices for multi-slice imaging by simultaneous multi-slice excitation. The processing circuitry acquires an echo signal by simultaneously exciting the first slice group and the slice for the navigator echo based on the first pulse sequence.