MRI Contrast Preparation Using Multiband RF Pulses
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Solution Overview
Problem
Current MRI techniques for rapid whole brain imaging face challenges in reducing scan time without compromising spatial resolution and image quality, as existing methods either suffer from significant losses in signal-to-noise ratio or require longer acquisition times.
Innovation Solution
The method involves a single contrast preparation performed simultaneously across multiple slice locations using multiband RF pulses, allowing for rapid image encoding and acquisition of high spatial resolution images by storing image contrast in longitudinal magnetization, which can be read out quickly, thereby reducing total data acquisition time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If single-shot three-dimensional echo volume imaging is used to reduce scan time, then acquisition time is reduced, but spatial resolution and image quality deteriorate due to longer echo trains causing distortions and blurring
Solution Approach 1:
The patent segments the imaging process into multiple shots, where each shot acquires a portion of the three-dimensional k-space data. This segmentation allows for shorter echo trains per shot, reducing distortions and blurring while maintaining overall fast acquisition by efficiently parallelizing the segmented data
Solution Approach 2:
The patent introduces a temporal dimension by acquiring multiple shots in sequence, each contributing to different portions of the three-dimensional image space. This multi-shot approach in the time domain enables high-resolution imaging without the severe distortions of single-shot methods
2Manufacturing precision
If multi-shot three-dimensional techniques are used to improve image quality, then spatial resolution is improved, but acquisition time increases
Solution Approach 1:
The patent applies preliminary contrast preparation (such as inversion recovery or saturation pulses) before the multi-shot acquisition sequence. This preliminary action prepares the magnetization in advance, allowing the subsequent multi-shot readout to proceed efficiently without requiring additional preparation time between shots
Solution Approach 2:
The patent optimizes acquisition parameters such as echo train length, repetition time, and flip angles to balance resolution and speed. By carefully selecting these parameters, the method achieves high spatial resolution while minimizing the total acquisition time penalty associated with multi-shot techniques
3Productivity
If echo shifting approaches are used to increase volume coverage efficiency, then coverage speed is improved, but signal-to-noise ratio deteriorates at higher magnetic fields
Solution Approach 1:
The patent modifies the echo shifting parameters, specifically the timing and duration of the shifting gradients, to optimize performance at high magnetic fields. By adjusting these parameters, the method maintains volume coverage efficiency while minimizing T2 and T2* decay effects that degrade signal-to-noise ratio at higher field strengths
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 enables efficient acquisition of high-quality images of significant imaging volumes like the whole human brain, reducing scan time while maintaining spatial resolution and signal-to-noise ratio, by utilizing multiband RF pulses for simultaneous contrast preparation and image encoding across multiple slice locations.
Implementation Method 1
a contrast preparation module that generates contrast-prepared magnetization substantially simultaneously in a plurality of subvolumes of a volume-of-interest by applying at least one multiband radio frequency (RF) pulse to the volume-of-interest
Data Source
AI summary
A method for acquiring image data from a plurality of slice locations in a subject with a magnetic resonance imaging (MRI) system is provided. The method includes directing the MRI system to perform a pulse sequence that includes performing a contrast preparation module configured to generate contrast-encoded longitudinal magnetization and an image encoding module configured to acquire image data from multiple slice locations substantially simultaneously. The contrast preparation module generally includes tipping longitudinal magnetization into the transverse plane to produce transverse magnetization, generating contrast-prepared transverse magnetization by establishing an image contrast in the transverse magnetization, and tipping the contrast-prepared magnetization back along the longitudinal axis to produce the contrast-encoded longitudinal magnetization.