MR Pulse Sequence Control for MRI Power Reduction
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Solution Overview
Problem
Diffusion weighted imaging (DWI) in magnetic resonance imaging systems faces high power consumption due to large and wide motion probing gradient (MPG) pulses, leading to prolonged scanning times as existing methods to reduce power consumption compromise image quality by decreasing signal-to-noise ratio.
Innovation Solution
An MR imaging system apparatus and method that applies a radio frequency excitation pulse followed by a first 90-degree, a 180-degree, and a second 90-degree refocusing pulse between two MPG pulses, reducing the width and power consumption of MPG pulses while maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the amplitudes of MPG pulses are decreased or time interval between MPG pulses is increased to reduce power consumption, then power consumption is reduced, but echo time increases and signal-to-noise ratio decreases significantly
Solution Approach 1:
The patent changes the parameters of the pulse sequence by introducing multiple refocusing pulses with specific timing and angles (90-degree and 180-degree pulses) between MPG pulses. This modifies the echo formation mechanism to allow shorter MPG pulse widths and lower amplitudes while maintaining adequate signal-to-noise ratio through the accumulated refocusing effect of multiple pulses.
Solution Approach 2:
The patent segments the single refocusing process into multiple refocusing pulses (first 90-degree refocusing pulse, 180-degree refocusing pulse, and second 90-degree refocusing pulse). This segmentation allows the signal to be refocused in multiple stages, enabling reduction of individual MPG pulse amplitudes while maintaining overall signal quality through cumulative refocusing.
2Measurement precision
If larger and wider MPG pulses are applied to achieve DWI, then imaging quality is improved, but power consumption increases significantly
Solution Approach 1:
The patent changes the pulse sequence parameters to use multiple refocusing pulses with specific timing, allowing MPG pulses to have smaller amplitudes and shorter widths while maintaining imaging quality through the cumulative effect of multiple refocusing operations.
Solution Approach 2:
The patent segments the refocusing process into multiple pulses applied between the MPG pulses, which allows the MPG pulses themselves to be less intense and shorter duration while achieving the same or better diffusion weighting effect through the combined refocusing sequence.
3Use of energy by moving object
If operation stops for power recovery after two MPG pulses, then power consumption is managed, but scanning time increases
Solution Approach 1:
The patent enables continuous operation without power recovery pauses by distributing the refocusing function across multiple pulses with appropriate timing. The pulse sequence is designed so that the gradient coil has sufficient time to settle between pulses while maintaining continuous signal acquisition, eliminating the need for operation stops.
Solution Approach 2:
The patent uses periodic application of refocusing pulses at specific intervals between MPG pulses. This periodic structure allows the system to manage power demands through regular, predictable pulse timing while maintaining continuous scanning without interruptions for power recovery.
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 reduces power consumption by 40% and shortens the minimum time of repetition, thereby decreasing scanning time without compromising image quality.
Implementation Method 1
The radio frequency system is used for emitting a radio frequency pulse with a certain frequency and power such that hydrogen protons within a detected object generate a resonance
Implementation Method 2
The gradient system is used for emitting a level selecting gradient pulse, a phase encoding gradient pulse and a frequency encoding gradient pulse to provide three-dimensional position information for the above MR signal
Data Source
AI summary
The present invention provides an apparatus and method for controlling a pulse sequence of a magnetic resonance (MR) imaging system, the MR imaging system comprising a radio frequency magnetic field coil and a gradient magnetic field coil, the apparatus for controlling a pulse sequence of the MR imaging system comprising a radio frequency driving unit and a gradient driving unit. The gradient driving unit is used for applying a first motion probing gradient (MPG) pulse and a second MPG pulse to the gradient magnetic field coil successively. The radio frequency driving unit is used for applying a radio frequency excitation pulse to the radio frequency magnetic field coil before the first MPG pulse is applied, and for applying a first 90-degree radio frequency refocusing pulse, a 180-degree radio frequency refocusing pulse and a second 90-degree radio frequency refocusing pulse to the radio frequency magnetic field coil successively between a time when the first MPG pulse is applied and a time when the second MPG pulse is applied.