MRI RF Pulse Phase Correction for Susceptibility Artifacts
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Solution Overview
Problem
Existing MRI technologies face challenges in producing high-quality images due to phase variations caused by bulk tissue susceptibility, leading to image distortion and signal loss, particularly in areas like the orbitofrontal region of the brain during susceptibility weighted imaging.
Innovation Solution
A method and apparatus for magnetic resonance imaging that design and use RF pulses based on phase criteria to nullify or mitigate phase variations, employing a processor to determine and apply a second train of RF pulses that counteract the phase distortions, thereby improving image quality and compensating for bulk tissue susceptibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional RF pulses are used for MRI scanning, then the imaging process is simple and fast, but phase variations occur due to bulk tissue susceptibility causing image distortion and signal loss
Solution Approach 1:
The patent performs a preliminary MRI scan to measure the actual phase distribution in the target region before the main imaging process. This preliminary measurement allows the system to characterize the phase variations caused by bulk tissue susceptibility, which are then used to design corrected RF pulses that compensate for these variations in subsequent scans, thereby improving image quality without excessive complexity
Solution Approach 2:
The patent modifies the phase parameters of RF pulses based on measured phase distributions. By adjusting the phase of transmit RF pulses according to the characteristics of the tissue being imaged, the system compensates for susceptibility-induced phase variations. This parameter adjustment allows conventional imaging sequences to produce higher quality images without requiring fundamentally new imaging approaches
2Reliability
If RF pulses are designed to nullify phase variations, then image distortion is reduced, but the RF pulse design becomes more complex requiring additional processing
Solution Approach 1:
The patent uses feedback from preliminary phase measurements to adjust RF pulse parameters. The system measures the actual phase distribution in the target region, then uses this information to design RF pulses with corrected phases. This feedback loop allows the system to adapt to the specific characteristics of each imaging scenario, improving signal stability while keeping the processing complexity manageable through iterative optimization
Solution Approach 2:
The system performs self-characterization by measuring its own phase variations during preliminary scans. Rather than requiring external calibration or complex pre-programming, the imaging system automatically measures the phase distribution in the target region and uses this information to generate appropriate correction pulses, reducing the need for external intervention and simplifying the overall process
3Manufacturing precision
If phase compensation is applied to the entire field of view, then phase artifacts are reduced globally, but processing time and computational load increase
Solution Approach 1:
The patent applies phase compensation selectively to the target region rather than uniformly across the entire field of view. By measuring and correcting phase variations only in the region of interest, the system achieves phase uniformity where it matters most while significantly reducing the computational load and processing time required compared to global correction approaches
Solution Approach 2:
The imaging process is divided into distinct segments: a preliminary scan for phase measurement, followed by main imaging with corrected pulses. The phase correction is applied segmentally to specific regions rather than treating the entire volume uniformly. This segmentation allows the system to balance image quality improvement with acceptable processing time by focusing computational resources on the most critical regions
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 solution effectively reduces phase-related artifacts and enhances image quality by designing RF pulses that match and counteract the phase variations, resulting in improved image reconstruction and reduced distortion, especially in areas affected by magnetic field inhomogeneities.
Implementation Method 1
magnetic resonance imaging (MRI) includes performing a first MRI scan on a target object using a first train of transmit radio frequency (RF) pulses
Implementation Method 2
determining a second train of transmit RF pulses designed based on the acquired data and a phase criterion... the determined second train of transmit RF pulses nulling a phase associated with the acquired data
Data Source
AI summary
In this disclosure, a process of imaging a target object using magnetic resonance (MR) includes an MRI scanner scanning the target object using a first transmit RF pulse. A processor associated with the MRI scanner can acquire magnitude and/or phase data associated with a first RF signal produced (or echoed) by the target object responsive to the MRI scan. The processor can determine a second transmit RF pulse for use to scan the target object based on the acquired data and according to a given phase criterion. The phase criterion can be configured to enforce mitigation of a phase distribution estimated based on the acquired data.