Segmented Multi-band ASL Imaging for Whole Brain Perfusion
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Solution Overview
Problem
Current ASL imaging techniques face challenges in achieving high-resolution whole brain perfusion data due to low signal-to-noise ratio (SNR) and increased acquisition times, particularly in the inferior brain region where long post-labeling delays are required, limiting spatial and temporal SNR efficiencies.
Innovation Solution
The implementation of a segmented multi-band acquisition technique, referred to as Time Efficient ASL Imaging with Segmented Multiband (TEAISM), which divides brain imaging into segments for the inferior, middle, and superior regions, using single-band EPI for the inferior region and multi-band EPI for the rest, allowing for optimized imaging with varying post-labeling delays to enhance SNR efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If multi-band EPI acquisition is used for whole brain ASL imaging, then total imaging time is reduced, but spatial and temporal SNR efficiency deteriorates in the inferior brain region
Solution Approach 1:
The patent divides the brain into inferior and superior regions, applying different acquisition strategies to each segment. The inferior brain is imaged with a first MB factor and the superior brain with a second MB factor, allowing optimized SNR efficiency in each region while maintaining reduced overall imaging time compared to single-band acquisition.
Solution Approach 2:
The patent applies different MB factors to different brain regions based on their specific requirements. The inferior brain region uses a first MB factor optimized for its longer arterial transit time, while the superior brain region uses a second MB factor, thereby achieving locally optimized SNR efficiency throughout the whole brain.
2Measurement precision
If single-band EPI acquisition is used for whole brain ASL imaging, then spatial and temporal SNR efficiency is maintained, but total imaging time increases
Solution Approach 1:
The patent segments the whole brain acquisition into multiple MB-EPI acquisitions with different MB factors, allowing parallel imaging of multiple slices in the superior region while maintaining sequential imaging in the inferior region, thereby reducing total imaging time while preserving SNR efficiency.
Solution Approach 2:
The patent dynamically adjusts the MB factor based on the brain region being imaged, using a first MB factor for the inferior brain and a second MB factor for the superior brain, allowing the system to adapt to regional variations in arterial transit time and optimize both speed and SNR efficiency.
3Productivity
If high MB factor is used in MB-EPI ASL imaging, then imaging speed increases, but SNR efficiency in inferior brain region remains comparable to single-band EPI
Solution Approach 1:
The patent applies a lower first MB factor to the inferior brain region where arterial transit time is longer, preserving SNR efficiency, while applying a higher second MB factor to the superior brain region where faster imaging is beneficial, thereby optimizing the balance between imaging speed and SNR efficiency in different regions.
Solution Approach 2:
The patent separates the brain into inferior and superior segments with different MB factors, allowing the inferior region to be imaged with slower, higher SNR-efficient parameters while the superior region uses faster, lower SNR parameters, achieving overall improved productivity without sacrificing inferior region quality.
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
TEAISM significantly improves spatial and temporal perfusion SNR efficiencies across the whole brain, reducing overall imaging time and minimizing leakage contamination, thereby increasing temporal SNR efficiency compared to single-band or multi-band acquisitions alone.
Implementation Method 1
perform an ASL preparation process, using the MRI system to magnetically label protons in arterial blood water
Implementation Method 2
Multi-band EPI (MB-EPI) uses multi-banded radio frequency (RF) pulses to simultaneously excite multiple spatially distributed slices
Implementation Method 3
where the superimposed signals acquired from the multiple slices are unwrapped via anti-aliasing reconstruction
Implementation Method 4
the need for more slices to cover the same volume resulting in prolonged delay times between labeling and signal acquisition during which labeled spins experience longitudinal relaxation
Data Source
AI summary
A method for generating a perfusion weighted image using ASL with segmented acquisitions includes dividing an anatomical area of interest into slices and performing an EPI acquisition process using an MRI system to acquire a control image dataset representative of the slices. An ASL preparation process is performed using the MRI system to magnetically label protons in arterial blood water upstream from the anatomical area of interest. Following a first time period, a multi-band EPI acquisition process is performed using the MRI system to acquire a first labeled image dataset representative of a first subset of the slices. Following a second time period, another multi-band EPI acquisition process is performed using the MRI system to acquire a second labeled image dataset representative of a second subset of the slices. A perfusion weighted image is generated by subtracting the first and second labeled image dataset from the control image dataset.