Integrated MRSI and fMRI Pulse Sequence for Concurrent Acquisition
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Solution Overview
Problem
Proton MR spectroscopic imaging (MRSI) and functional MRI (fMRI) modalities have long scan times, making it challenging to collect both data sets in a single session, and current water suppression methods are time-consuming and inefficient, especially when trying to integrate both modalities for clinical and research applications.
Innovation Solution
The simultaneous acquisition of multiple MRI contrasts is achieved by integrating spatial and spatial-spectral encoding modules into the water suppression module, allowing for concurrent measurement of tissue water and BOLD-contrast signal changes during MRSI acquisition, which reduces scan time and enables the integration of fMRI and MRSI data in a single scan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional MRSI and fMRI scan sequences are used separately, then data quality and signal accuracy are maintained, but total scan time becomes excessively long (several minutes to half an hour for each modality)
Solution Approach 1:
The patent combines MRSI and fMRI into a single integrated pulse sequence where water suppression modules are merged with spatial and spatial-spectral encoding modules. This allows concurrent acquisition of both modalities in one scan session, reducing total time from separate scans (several minutes to half an hour each) to a single unified acquisition while maintaining data quality through coordinated pulse sequence design.
Solution Approach 2:
The water suppression module is designed to perform multiple functions simultaneously: suppressing water signal, providing spatial encoding, and enabling spectral encoding for both MRSI and fMRI. This multi-functional approach allows a single pulse sequence to generate both metabolic and functional imaging data without requiring separate dedicated sequences.
2Loss of time
If water suppression is performed using conventional multi-pulse schemes (WET, VAPOR), then water signal is effectively suppressed, but acquisition time increases significantly
Solution Approach 1:
The patent merges water suppression with spatial and spatial-spectral encoding into a single integrated module. Instead of performing water suppression as a separate multi-pulse sequence (WET, VAPOR) that takes several minutes, the water suppression is combined with the encoding process, allowing concurrent acquisition of multiple contrasts including water-suppressed MRSI and fMRI signals within the same pulse sequence.
Solution Approach 2:
The integrated pulse sequence maintains continuous useful action by performing water suppression, spatial encoding, and spectral encoding within a single continuous acquisition window. This eliminates the need for separate water suppression scans and maintains signal quality throughout the acquisition by keeping the system in a steady-state condition.
3Measurement precision
If water reference scans are acquired separately to provide concentration reference and eddy current correction, then measurement accuracy is improved, but total scan time doubles or more
Solution Approach 1:
The patent combines water reference acquisition with the main MRSI and fMRI scan by integrating water reference modules into the pulse sequence. The water reference signal is acquired concurrently with the water-suppressed and echo-planar imaging modules, allowing simultaneous extraction of concentration reference and eddy current correction data without requiring separate reference scans.
Solution Approach 2:
The water reference module is designed to serve multiple purposes within a single acquisition: providing concentration reference for metabolite quantification, enabling eddy current correction, and maintaining signal stability. This multi-functional reference acquisition eliminates the need for separate reference scans that would otherwise double or more the total acquisition time.
4Measurement precision
If conventional fMRI and MRSI are acquired with different spatial resolutions, then each modality achieves optimal signal quality, but integration and clinical application become difficult
Solution Approach 1:
The patent applies different encoding strategies to different spatial regions and signal types within the same pulse sequence. Spatial encoding modules provide high-resolution anatomical information where needed, while spectral encoding modules optimize metabolite detection in specific voxels. This allows the system to maintain optimal signal quality for both fMRI and MRSI while enabling integration through unified data acquisition.
Solution Approach 2:
The integrated pulse sequence provides universal capability to acquire both fMRI and MRSI data with compatible spatial and spectral resolution. By incorporating both spatial encoding and spatial-spectral encoding modules, the system can generate datasets that are directly comparable and integrable, facilitating clinical applications such as mapping eloquent cortex near brain lesions without requiring post-processing resampling or registration.
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 acquisition time, enhances patient comfort, and facilitates the integration of multiple imaging modalities, including fMRI and MRSI, while maintaining sensitivity, thus overcoming the limitations of conventional methods and enabling more efficient clinical and research imaging protocols.
Implementation Method 1
Multi-pulse T1- and B1 compensated water suppression schemes, such as water suppression enhanced through T1 effects (WET) and water suppression with variable power radiofrequency (RF) pulses and optimized relaxation delays (VAPOR), are widely used to mitigate the effects of multiple water components with different T1 values
Implementation Method 2
integrating spatial and spatial-spectral encoding modules into the water suppression module, allowing for concurrent measurement of tissue water and BOLD-contrast signal changes
Implementation Method 3
integrating spatial and spatial-spectral encoding modules into the water suppression module
Implementation Method 4
integrating spatial and spatial-spectral encoding modules into the water suppression module
Implementation Method 5
concurrent measurement of tissue water and BOLD-contrast signal changes during MRSI acquisition
Data Source
AI summary
A method of obtaining multiple MRI contrasts of a subject comprising the steps of concurrently acquiring an MRSI and fMRI data in the same scan.