MRI Frequency Band Segmentation for Metal Artifact Reduction
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Solution Overview
Problem
Current MRI imaging methods require long imaging times to reduce image distortion caused by metal implants, with a trade-off between imaging time and distortion reduction effectiveness.
Innovation Solution
An MRI device with a control unit that sets multiple frequency bands with overlapping bandwidths, irradiating a high-frequency magnetic field pulse across these bands to generate and composite images, optimizing bandwidth around a specific frequency to minimize distortion while shortening imaging time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple frequency bands are used to reduce image distortion, then distortion reduction effect is improved, but imaging time increases
Solution Approach 1:
The frequency band is segmented into multiple sub-bands, with the center frequency band having a narrower bandwidth and surrounding frequency bands having progressively wider bandwidths. This segmentation allows the imaging process to cover a broad frequency range while spending more time on the critical center frequency region, thereby reducing overall image distortion without requiring uniformly long imaging time across all frequency bands.
Solution Approach 2:
Different bandwidth allocations are applied to different frequency regions: the center frequency band receives a narrower bandwidth for detailed distortion reduction, while surrounding frequency bands receive progressively wider bandwidths. This local quality approach optimizes the trade-off between distortion reduction effectiveness and imaging time by applying stricter sampling only where most needed.
2Loss of time
If the number of frequency bands is reduced to shorten imaging time, then imaging time is shortened, but distortion reduction effect decreases
Solution Approach 1:
The bandwidth of frequency bands is made dynamic rather than uniform: the center frequency band has a narrower bandwidth that is optimized for distortion reduction, while surrounding frequency bands have progressively wider bandwidths. This dynamic bandwidth allocation allows the system to adapt the sampling density to the actual distortion characteristics at different frequencies, reducing total imaging time while maintaining distortion reduction effectiveness.
Solution Approach 2:
The bandwidth parameter is changed across different frequency bands according to a specific pattern: the center frequency band uses a narrower bandwidth and surrounding frequency bands use progressively wider bandwidths. This parameter change strategy allows the imaging system to achieve effective distortion reduction with fewer total frequency bands compared to uniform bandwidth approaches, thereby shortening imaging time without sacrificing image quality.
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 allows for reduced imaging time while effectively minimizing image distortion caused by metal implants, achieving a balance between time efficiency and distortion reduction.
Implementation Method 1
a static magnetic field generation unit configured to generate a uniform static magnetic field in a space for accommodating a subject
Implementation Method 2
a transmission unit configured to irradiate a high-frequency magnetic field pulse for exciting the subject
Implementation Method 3
a reception unit configured to receive an NMR signal generated by the subject irradiated with the high-frequency magnetic field pulse
Data Source
AI summary
A magnetic resonance imaging device includes a control unit configured to set a plurality of frequency bands within a predetermined frequency range. A subject is caused to be irradiated with a high-frequency magnetic field pulse having one of the frequency bands from a transmission unit. A reception unit is caused to receive a nuclear magnetic resonance (NMR) signal generated by the subject. An image generation unit is caused to generate an image from the NMR signal while changing the frequency band. A plurality of images corresponding to the plurality of frequency bands are obtained, and a composite of the plurality of images is obtained. The frequency bands are set so that adjacent frequency bands partially overlap each other. A bandwidth of the frequency bands is narrowest for the frequency band including a specific frequency within the frequency range, and widens in a direction away from the specific frequency.