MRI Refocusing Sequence With Balancing Gradients for Artifact Reduction
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Solution Overview
Problem
Magnetic resonance imaging (MRI) sequences suffer from artifacts due to nonlinear concomitant fields generated during scans, causing phase errors, signal loss, and image blurring, which are not adequately addressed by existing methods.
Innovation Solution
A magnetic resonance imaging sequence with a radio-frequency excitation pulse, refocusing pulses, and balancing pulses, along with specific gradient pulses, is designed to compensate for concomitant fields by adjusting gradient amplitudes and durations to minimize artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ideal gradient pulses are used to make the magnetic field change linearly, then the magnetic field linearity is improved, but nonlinear concomitant fields are inevitably generated causing phase errors and image artifacts
Solution Approach 1:
The patent applies preliminary anti-action by introducing compensating gradient pulses before the main imaging sequence to pre-counteract the nonlinear concomitant fields. These compensating pulses are designed to generate opposite phase errors that cancel out the harmful concomitant field effects, thereby reducing image artifacts while maintaining magnetic field linearity.
Solution Approach 2:
The patent employs parameter changes by adjusting the amplitude and duration of gradient pulses to optimize the balance between magnetic field linearity and concomitant field suppression. By varying gradient strengths and timing parameters, the system achieves reduced phase errors and improved image quality without sacrificing the linear magnetic field requirement.
2Manufacturing precision
If compensating gradient pulses are added to reduce concomitant fields, then image quality is improved, but the sequence complexity increases
Solution Approach 1:
The patent merges the compensating gradient pulses with the existing imaging sequence structure, integrating artifact reduction functionality into the standard pulse sequence framework. By combining compensation elements with routine imaging operations, the system achieves improved image quality without requiring separate dedicated compensation sequences, thereby limiting the increase in overall complexity.
Solution Approach 2:
The patent implements preliminary action by pre-calculating and pre-programming the compensating gradient parameters based on the specific imaging protocol. This allows the compensation strategy to be prepared in advance, reducing real-time computational complexity and enabling automated implementation of image quality improvement without burdening the scanning process.
3Manufacturing precision
If gradient pulse amplitudes are increased to improve image resolution, then image quality is improved, but the scan time increases due to longer gradient durations
Solution Approach 1:
The patent applies dynamics by implementing variable gradient pulse schemes where the amplitude and duration are dynamically adjusted based on the specific imaging requirements and tissue characteristics. This allows the system to use higher gradient amplitudes only when necessary for resolution, while reducing gradient strength and duration in other phases, thereby optimizing the trade-off between image quality and scan time.
Solution Approach 2:
The patent employs parameter changes by optimizing gradient pulse characteristics including amplitude, duration, and timing to achieve the desired resolution with minimal time penalty. By carefully tuning these parameters and using parallel imaging techniques, the system maintains high resolution while reducing the overall scan duration through efficient parameter management.
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
The proposed sequence effectively reduces artifacts by balancing concomitant fields, improving image quality and reducing scanning time without increasing echo spacing.
Implementation Method 1
Magnetic resonance imaging technology utilizes electromagnetic principles to generate and acquire image information
Implementation Method 2
Magnetic resonance imaging technology utilizes electromagnetic principles to generate and acquire image information by executing imaging sequences
Implementation Method 3
such concomitant fields cause undesired phase accumulation, resulting in phase errors between echo signals
Data Source
AI summary
A magnetic resonance system, a magnetic resonance imaging sequence, and an optimization method are provided. The imaging sequence includes: a radio-frequency excitation pulse; a first radio-frequency refocusing pulse and a second radio-frequency refocusing pulse sequentially applied after the radio-frequency excitation pulse; original gradient pulses including a right-side original pulse and a left-side original pulse, the right-side original pulse being applied between the center of the first radio-frequency refocusing pulse and the center of the second radio-frequency refocusing pulse, the left-side original pulse being applied between the center of the radio-frequency excitation pulse and the center of the first radio-frequency refocusing pulse, and the left-side original pulse including a first gradient pulse corresponding to the radio-frequency excitation pulse; and a first balancing pulse located within a first time period between the end point of the first gradient pulse and the starting point of the first radio-frequency refocusing pulse and including a positive pulse and a negative pulse located on a first gradient axis.