Variable-Flip-Angle Stimulated Echoes for Single-Shot Diffusion MRI
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing diffusion-weighted magnetic resonance imaging (DWI) techniques face challenges with lengthy acquisition times due to the need for multiple b-values and diffusion times, leading to patient discomfort, motion-induced image misregistration, and reduced data reliability.
Innovation Solution
A magnetic resonance imaging system using a pulse sequence that incorporates multiple b-values and diffusion times within a single scan, employing a stimulated echo with variable flip angles and crusher gradients to generate diffusion-weighted images, allowing for simultaneous acquisition of multiple diffusion-weighted images with varying b-values and times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple b-values and diffusion times are acquired using conventional SE-EPI or STEAM sequences, then comprehensive diffusion data is obtained, but acquisition time increases significantly
Solution Approach 1:
The patent combines multiple diffusion-weighted imaging acquisitions with different b-values and diffusion times into a single shot using stimulated echo echo-planar imaging. Multiple diffusion times are incorporated during the mixing time period, allowing simultaneous acquisition of multiple diffusion-weighted images without repeating the entire sequence for each b-value or diffusion time combination.
Solution Approach 2:
The stimulated echo sequence maintains continuous useful action by utilizing the mixing time period to incorporate multiple diffusion times without interrupting the imaging process. The longitudinal magnetization is restored and can be repeatedly excited during the mixing time, enabling continuous acquisition of diffusion-weighted images with varying diffusion times and b-values in a single shot.
2Measurement precision
If sequence is repeated for multiple b-values, then complete diffusion-weighted dataset is acquired, but patient compliance deteriorates due to long scan times
Solution Approach 1:
The patent merges multiple diffusion-weighted imaging acquisitions into a single shot by utilizing stimulated echo with variable mixing times. Different diffusion times are incorporated during the mixing time period, and multiple b-values are achieved through different gradient strengths, allowing complete diffusion dataset acquisition in one continuous scan without repeating the sequence multiple times.
3Reliability
If multiple scans are performed for different b-values, then comprehensive diffusion data is collected, but motion-induced image misregistration increases
Solution Approach 1:
The patent combines multiple diffusion-weighted imaging acquisitions with different b-values and diffusion times into a single shot acquisition. By acquiring all necessary diffusion data in one continuous scan rather than repeating the sequence multiple times, the patent eliminates motion-induced misregistration between separate scans while maintaining comprehensive diffusion data collection.
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 by up to four-fold, improves patient compliance, and enhances data reliability by minimizing motion-induced errors, while maintaining accurate quantitative diffusion analysis.
Implementation Method 1
a stimulated echo configured to incorporate a set of multiple b-values and a set of readouts to generate diffusion-weighted images
Implementation Method 2
STEAM has been proposed to enable a broad range of diffusion times during the TM, when the magnetization is restored along the longitudinal axis, thus avoiding T2 decay while experiencing only a minor to moderate T1 effect
Implementation Method 3
one or more crusher gradients or spoiler gradients are used to select a stimulated echo signal corresponding to a specific and desired b-value
Implementation Method 4
diffusion-weighted imaging (DWI) has become a powerful non-invasive technique to characterize microenvironment and infer tissue microstructures
Data Source
AI summary
A time-efficient diffusion magnetic resonance imaging systems and methods are provided that can produce multiple diffusion-weighted images with different b-values in one repetition time, and/or multiple diffusion-weighted images with different diffusion times in one repetition time, both by utilizing a train of stimulated echoes. Each stimulated echo in the train of stimulated echoes is generated by a re-excitation radio-frequency (RE) pulse with a variable flip angle, following an initial 90° excitation RE pulse and a subsequent 90° restoration RE pulse.