Single Continuous Composite RF Pulse for MRI Fat Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Composite RF Pulses technique for fat suppression in MRI is ineffective at high B0 field strengths due to large phase shifts and resulting phase errors, leading to incorrect identification of water and fat signals.
Innovation Solution
A single continuous composite pulse is used, with specific pulse portions and phases to independently manipulate water and fat magnetization, reducing phase errors by allowing shorter time delays without exceeding pulse amplitude limits, and enabling effective fat suppression across varying field strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Composite RF Pulses technique is used for fat suppression, then fat suppression is effective at low field strengths, but phase errors increase and technique fails at high B0 field strengths
Solution Approach 1:
The patent changes the temporal parameters of the RF pulse by using a continuous pulse design with optimized duration and phase transitions, replacing the conventional multi-pulse sequence. This allows the pulse to achieve the necessary phase shifts for fat suppression while minimizing the cumulative phase errors that occur in conventional techniques at high field strengths
Solution Approach 2:
The patent employs a continuous RF pulse rather than discrete pulses separated by delays. This continuous action maintains consistent phase relationships throughout the pulse duration, preventing the phase errors that accumulate in conventional techniques when multiple pulses are separated by time delays, especially at high B0 field strengths
2Reliability
If large phase shifts are used in Composite RF Pulses technique, then fat suppression is achieved, but large time delays are required between pulses which cause phase errors in B0 inhomogeneity
Solution Approach 1:
The patent merges multiple discrete RF pulses with time delays into a single continuous pulse. This consolidation eliminates the gaps between pulses where phase errors accumulate due to B0 inhomogeneity, while still achieving the necessary phase shifts for fat suppression through continuous phase modulation within the single pulse
Solution Approach 2:
The continuous pulse design performs all necessary phase shifts and magnetization manipulations within a single uninterrupted time window, eliminating the need for subsequent corrective actions that would be required to fix phase errors if conventional multi-pulse sequences were used
3Measurement precision
If multiple discrete pulses are used with time delays, then phase shifts between water and fat are created, but phase errors increase with B0 field strength
Solution Approach 1:
The patent optimizes the temporal and phase parameters of the continuous RF pulse to achieve the required water-fat phase differentiation. By carefully controlling the pulse duration, amplitude, and phase evolution within the continuous pulse, the method achieves accurate phase shifts without the field-strength-dependent errors that plague conventional multi-pulse sequences
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 single continuous composite pulse effectively suppresses fat signals while maintaining water signal integrity, even at high B0 field strengths, improving image quality by accurately differentiating between water and fat magnetization.
Implementation Method 1
Magnetic Resonance Imaging ('MRI') is a medical imaging technique used to visualize tissues and other internal structures of the body
Implementation Method 2
determining a time required to have spins of protons corresponding to the first chemical species acquire a phase shift of 90 degrees relative to spins of protons corresponding to second chemical species
Data Source
AI summary
A method for manipulating magnetic resonance signals of a first chemical species and a second chemical species includes determining a time required to have spins of protons corresponding to the first chemical species acquire a phase shift of 90 degrees relative to spins of protons corresponding to second chemical species. A first pulse portion having a pulse amplitude and a first constant phase is defined. A second pulse portion having the pulse amplitude and a second constant phase, the second constant phase being different from said first constant phase by a multiple of 90 degrees is also defined. Next, a single continuous composite pulse is generated by concatenating the first pulse portion and the second pulse portion, wherein the single continuous composite pulse has a duration such that a time difference between center of the first pulse portion and center of the second pulse portion corresponds to the determined time. Then, the single continuous composite pulse is applied to a plurality of radio frequency coils.