MRI Motion Compensation via Camera-Gated Pulse Sequences
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Solution Overview
Problem
MRI imaging is affected by subject motion, leading to artifacts and requiring longer imaging times or data deletion/recapture, which is challenging to synchronize with MRI and camera systems.
Innovation Solution
An MRI apparatus with a control unit that divides the imaging pulse sequence into small sequences based on camera frame rate, detecting subject displacement before executing each sequence, and waiting for the next frame if motion exceeds allowable limits, thereby reducing the impact of subject motion without prolonging imaging time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If MRI imaging is performed for tens of minutes to one hour to ensure complete data acquisition, then image quality and completeness are improved, but subject motion artifacts increase and imaging reliability deteriorates
Solution Approach 1:
The system performs preliminary motion detection using camera images before acquiring each MR data set. Based on the detection results, the system decides whether to proceed with imaging or skip to the next phase encoding step, preventing motion-corrupted data acquisition in advance
Solution Approach 2:
The system establishes a feedback loop where camera images are continuously monitored during MRI acquisition, motion is detected in real-time, and the imaging process is dynamically adjusted by skipping problematic phases or repeating acquisitions based on detected motion levels
2Reliability
If MRI imaging time is extended to accommodate motion detection and verification, then motion artifacts are reduced, but imaging efficiency and productivity decrease
Solution Approach 1:
Instead of verifying motion for every single phase encoding step, the system performs motion detection at selected intervals and uses predictive logic to determine whether intermediate steps are likely to be free of motion, reducing the frequency of full verification cycles
Solution Approach 2:
The imaging pulse sequence is divided into multiple phase encoding steps that can be independently executed or skipped. The system segments the acquisition process to allow selective repetition of only those specific steps affected by motion, rather than repeating the entire sequence
3Manufacturing precision
If echo signal acquisition is repeated to compensate for motion-corrupted data, then data completeness is improved, but imaging time increases significantly
Solution Approach 1:
The system repeats only the specific phase encoding steps that were corrupted by motion, rather than repeating all 256 or 512 echoes. This partial repetition approach maintains data completeness while minimizing additional imaging time
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 influence of subject motion on MRI imaging without the need for data deletion or recapture, maintaining imaging efficiency by synchronizing camera and MRI operations.
Implementation Method 1
a static magnetic field generating device for applying a static magnetic field to an imaging region
Implementation Method 2
an imaging unit for applying a high-frequency magnetic field pulse and a gradient magnetic field pulse to a subject arranged in the imaging region and acquiring a nuclear magnetic resonance signal generated from the subject
Data Source
AI summary
An object of the invention is to perform MRI imaging which is less likely to be affected by a body motion without prolonging an imaging time. The control unit takes in images captured by the camera at a predetermined frame rate. The imaging pulse sequence is divided into small sequences at a time width corresponding to the frame rate of the camera. The control unit, before causing the imaging unit to execute one small sequence, detects a displacement of the subject with respect to a predetermined reference position or a motion speed of the subject based on an image of the latest frame, and causes the imaging unit to execute the small sequence when a detection result is within a predetermined allowable range and waits until an image of a next frame is taken in according to the frame rate without causing the imaging unit to execute the small sequence when the detection result exceeds the allowable range.