Hadamard RF Excitation for Faster MRI Without Image-Quality Loss
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Solution Overview
Problem
Current MRI technologies face challenges in achieving faster scan times without compromising image quality, particularly with Simultaneous Multi-Slice (SMS) imaging, due to limitations in applying inversion prepared sequences and the complexity of multiband techniques, leading to longer scan times and reduced patient throughput.
Innovation Solution
Implementing a Hadamard encoded radiofrequency (RF) excitation pulse sequence combined with secondary RF excitation pulses to generate a composite RF pulse, which is used to accelerate MRI scans by increasing the total acceleration factors through methods like parallel imaging and simultaneous multi-slice techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If Simultaneous Multi-Slice (SMS) imaging is used to reduce scan times, then scan time is reduced, but the ability to apply inversion prepared sequences is limited and image quality may be compromised
Solution Approach 1:
The patent segments the k-space acquisition into multiple slices and applies SMS techniques to excite multiple slices simultaneously. By dividing the imaging task into separate slice acquisitions that can be performed in parallel, the system reduces scan time while maintaining image quality through proper slice encoding and reconstruction.
Solution Approach 2:
The patent modifies RF pulse parameters by using adiabatic inversion pulses with specific flip angles and duration to enable SMS imaging. By changing the pulse parameters (flip angle, duration, frequency) to match the SMS acquisition scheme, the system achieves both fast scanning and high image quality without compromising either aspect.
2Loss of time
If Multiband technology is combined with parallel imaging techniques to accelerate scans, then scan time is reduced, but signal-to-noise ratio penalties occur
Solution Approach 1:
The patent uses multiple receive coils to acquire signals from different slices simultaneously. By copying the signal acquisition process across multiple spatial locations (slices) using parallel imaging, the system reduces scan time while maintaining SNR through the use of multiple coil elements that provide independent signal paths.
Solution Approach 2:
The patent adds the temporal dimension to the imaging process by acquiring multiple slices simultaneously in a single TR cycle. This dimensional change from sequential slice acquisition to parallel slice excitation reduces scan time without the SNR penalties associated with traditional acceleration methods.
3Reliability
If traditional adiabatic inversion pulses are used, then inversion preparation is achieved, but compatibility with SMS techniques is limited
Solution Approach 1:
The patent makes the inversion pulse parameters dynamic by adjusting flip angles, durations, and frequency components to match the SMS acquisition scheme. This dynamic adaptation allows the same adiabatic inversion pulse to be compatible with SMS techniques, achieving both inversion preparation and fast scanning.
Solution Approach 2:
The patent designs the RF pulse sequence to serve multiple functions: adiabatic inversion, slice selection, and SMS encoding. By making the pulse sequence multi-functional, it achieves inversion preparation while being compatible with SMS techniques, eliminating the need for separate 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
This approach significantly reduces scan times, enhances patient comfort, and increases operational efficiency by allowing more patients to be scanned in a day, while maintaining image quality and utilizing existing MRI hardware effectively.
Implementation Method 1
applying a Hadamard encoded radiofrequency (RF) excitation pulse sequence to adjacent slices within a magnetic resonance imaging (MRI) scanner to generate Hadamard encoded adjacent slices
Implementation Method 2
generating the MR image of the object using the composite RF pulse
Data Source
AI summary
A computer-implemented method for generating a magnetic resonance (MR) image of an object includes applying, via a processing system comprising one or more processors, a Hadamard encoded radiofrequency (RF) excitation pulse sequence to adjacent slices within a magnetic resonance imaging (MRI) scanner to generate Hadamard encoded adjacent slices; multiplexing, via the processing system, the Hadamard encoded adjacent slices with secondary RF excitation pulses to generate a composite RF pulse; and generating, via the processing system, the MR image of the object using the composite RF pulse.