MRI Pulse Sequence Merging Gradient Spin Echo for T2 T2* Acquisition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current magnetic resonance imaging (MRI) techniques face challenges in efficiently acquiring both true transverse relaxation time (T2) and apparent transverse relaxation time (T2*) maps, as existing methods like the gradient echo (GE) system only provide T2* and require longer imaging times for T2-weighted images, making it difficult to obtain multiple subject parameter maps quickly.
Innovation Solution
Implementing a combined gradient echo and spin echo imaging sequence that allows for the calculation of multiple subject parameters by using gradient echo signals for one parameter and spin echo signals for another, enabling the acquisition of T2 maps without extending imaging time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a gradient echo imaging sequence is used to acquire T2* maps, then imaging speed is improved, but the ability to acquire true T2 maps is lost
Solution Approach 1:
The patent combines gradient echo and spin echo imaging sequences into a single pulse sequence structure. The gradient echo component enables fast imaging for T2* measurement, while the spin echo component (using a 180° refocusing pulse) enables true T2 measurement. This merging allows both measurement types to be obtained in one imaging protocol without requiring separate sequences, thus resolving the contradiction between imaging speed and T2 measurement capability.
2Measurement precision
If a spin echo imaging sequence is used to acquire T2 maps, then T2 measurement accuracy is improved, but imaging time is increased
Solution Approach 1:
By merging the spin echo and gradient echo sequences into a single pulse sequence, the patent performs both T2 and T2* measurements within one imaging protocol. The spin echo component provides accurate T2 measurement using the 180° refocusing pulse, while the gradient echo component enables faster imaging. This combination avoids the need to choose between sequence types, thereby obtaining T2 accuracy without the full imaging time penalty of standalone spin echo sequences.
3Measurement precision
If multiple parameter maps (T2 and T2*) are acquired separately, then measurement completeness is improved, but imaging time is increased
Solution Approach 1:
The patent merges the acquisition of T2 and T2* parameter maps into a single imaging protocol by incorporating both spin echo and gradient echo components in one pulse sequence. The spin echo component acquires T2 information while the gradient echo component acquires T2* information simultaneously within the same imaging cycle. This merging approach obtains both parameter maps without requiring separate imaging sessions, thus improving measurement completeness while minimizing total imaging time.
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 the rapid acquisition of multiple parameter maps, including T2, T2*, and other parameters, by utilizing the waiting time after gradient echo measurements, thus minimizing overall imaging time.
Implementation Method 1
A magnetic resonance imaging (MRI) apparatus acquires an image of atomic nuclear density (proton density) of a tissue and an images of a moving part such as blood flow, using signal intensity and phase information of a nuclear magnetic resonance signal obtained from an atom constituting the tissue of a subject, mainly an atomic nucleus of a hydrogen atom.
Implementation Method 2
a measurement unit that applies a high-frequency magnetic field and a gradient magnetic field to a subject and measures a nuclear magnetic resonance signal emitted from the subject
Data Source
AI summary
A plurality of subject parameter maps are acquired at high speed. In addition to using an imaging sequence for generating both a gradient echo and a spin echo in a single imaging sequence, one or more parameters such as the longitudinal relaxation time T1 and the apparent transverse relaxation time T2* are calculated using the gradient echo and another parameter such as true transverse relaxation time T2 is calculated using the spin echo. When a value of one parameter is calculated, a value of the parameter calculated at the time of calculating the other parameter can be used.