Simultaneous Multislice MRI Pulse Sequences With Navigator Echoes
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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 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 and method that designs a pulse sequence for simultaneous multi-slice excitation and navigator echo acquisition, allowing for motion correction and improved image reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If navigator signals are acquired separately from intended imaging, then motion 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 simultaneous pulse sequence. The processing circuitry is configured to acquire both navigator echo signals and imaging echo signals during the same excitation cycle, eliminating the need for separate acquisition processes and maintaining timing simultaneity while enabling motion correction
Solution Approach 2:
The pulse sequence is designed to serve multiple functions simultaneously: it performs both motion correction (through navigator signal acquisition) and intended imaging (through imaging signal acquisition) in a single execution cycle. This multi-functionality allows the system to maintain desired signal-to-noise ratio and contrast while providing motion correction capabilities
2Reliability
If navigator signals are acquired alternately with intended imaging, then motion information can be obtained, but imaging time is increased due to loss of simultaneity
Solution Approach 1:
The patent merges the acquisition of navigator signals and imaging signals into a single simultaneous pulse sequence execution. The processing circuitry is configured to acquire both types of signals during the same excitation cycle, eliminating the need for alternating acquisition processes and reducing total imaging time while maintaining motion correction capabilities
3Measurement precision
If a pulse sequence is designed under tuned conditions for desired SNR or contrast, then imaging quality is optimized, but additional navigator signal acquisition disrupts the timing and reduces simultaneity
Solution Approach 1:
The patent designs a universal pulse sequence that simultaneously performs both motion correction (navigator signal acquisition) and intended imaging (imaging signal acquisition) in a single execution cycle. This multi-functional design maintains the optimized SNR and contrast achieved through tuned conditions while avoiding the disruption caused by separate navigator acquisition processes
Solution Approach 2:
The patent segments the pulse sequence into distinct navigator signal acquisition components and imaging signal acquisition components within a single unified sequence. This segmentation allows each component to be optimized independently while maintaining overall timing simultaneity, thus preserving desired SNR and contrast without excessive complexity
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, improving image quality and reducing imaging time while maintaining desired signal-to-noise ratio and contrast.
Implementation Method 1
magnetic resonance imaging apparatus includes processing circuitry configured to: design 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; and acquire an echo signal by simultaneously exciting the first slice group and the slice for the navigator echo based on the first pulse sequence
Data Source
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AI summary
According to one embodiment, a magnetic resonance imaging apparatus (1) includes processing circuitry (51). The processing circuitry (51) designs (511) 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 (51) acquires (512) an echo signal by simultaneously exciting the first slice group and the slice for the navigator echo based on the first pulse sequence.