Spatially Selective MRI Preparation Pulses for Multi-Region T1 Mapping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing magnetic resonance imaging (MRI) techniques for generating T1 maps are inefficient, requiring long times and subject cooperation due to the need for magnetization equilibrium between different regions of interest, limiting the ability to acquire multiple T1 maps during a single breath-hold.
Innovation Solution
The method involves generating spatially selective preparation pulses that excite only the region of interest, allowing for simultaneous or rapid acquisition of T1 maps from multiple regions without waiting for magnetization equilibrium, using a combination of excitation pulses and magnetic field gradients to minimize interference between adjacent regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional MRI sequences (MOLLI, SASHA, SAPPHIRE) are used to generate T1 maps for multiple regions of interest, then comprehensive tissue characterization is achieved, but the total scan time becomes excessively long due to requiring magnetization equilibrium between sequences
Solution Approach 1:
The patent divides the imaging space into multiple disjoint regions of interest along the first spatial axis. Each region is imaged using spatially selective preparation pulses that affect only that specific region. This segmentation allows independent T1 mapping for each region without requiring magnetization equilibrium between regions, thereby reducing total scan time while maintaining T1 mapping accuracy for each segmented region.
Solution Approach 2:
The patent applies spatially selective preparation pulses with different characteristics to different regions of interest. Each region receives a customized preparation pulse sequence tailored to its specific imaging requirements, allowing optimized T1 mapping for each local region while avoiding the need for global magnetization equilibrium that would constrain all regions.
2Reliability
If multiple T1 maps are acquired during separate breath-holds, then sufficient time is allowed for magnetization recovery, but motion artifacts increase and clinical feasibility decreases
Solution Approach 1:
The patent merges multiple T1 mapping acquisitions into a single breath-hold by using spatially selective preparation pulses that allow simultaneous or rapidly sequential imaging of multiple regions without requiring magnetization recovery between regions. This combining approach maintains image quality by reducing motion artifacts while significantly improving clinical feasibility through shorter scan duration and simplified patient cooperation.
3Productivity
If spatially selective preparation pulses are used to image multiple regions rapidly, then scan time is reduced, but interference between adjacent regions may occur
Solution Approach 1:
The patent extracts and eliminates the harmful magnetization effects from adjacent regions by using spatially selective preparation pulses with different frequency offsets and gradient polarities. Each region's preparation pulse is specifically designed to affect only its target region while leaving other regions unaffected, thereby preventing interference and maintaining T1 mapping accuracy despite rapid sequential imaging.
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 the time required to generate multiple T1 maps, enabling their acquisition during a single breath-hold and improving clinical feasibility by minimizing motion artifacts and scan costs.
Implementation Method 1
generating an excitation pulse at the same time as generating a magnetic field gradient along a first spatial axis
Implementation Method 2
generating a spatially selective preparation pulse for exciting the region of interest of the subject
Implementation Method 3
an inversion pulse is generated and followed by the acquisition of five images... an inversion pulse means a 180 degrees excitation pulse that acts to flip the initial longitudinal magnetization of a subject's tissue to point opposite to the direction of the main magnetic field
Implementation Method 4
a saturation pulse is generated followed by an image acquisition... a saturation pulse refers to a 90 degrees excitation pulse that acts to tip the initial longitudinal magnetization of a subject's tissue into the transverse magnetization plane
Implementation Method 5
T1 relaxation time, also known as the spin-lattice or longitudinal relaxation time, is a measure of how fast the nuclear spin magnetization returns to its equilibrium state after an excitation pulse
Data Source
AI summary
In a method and apparatus for performing magnetic resonance (MR) imaging for generating multiple T1 maps of separate regions of interest of a subject along a first spatial axis, multiple MR pulse sequences are generated, each MR pulse sequence being for imaging a respective one of the separate regions of interest of the subject. In order to generate each of the plurality of MR pulse sequences, a spatially selective preparation pulse is generated exciting the region of interest of the subject and a number of imaging sequences that follow the application of the spatially selective preparation pulse are generated. MR imaging data are acquired during the generation of the multiple imaging sequences. The multiple MR pulse sequences are generated during a period not exceeding 30 seconds.