Gradient Echo Pulse Sequence with RF Phase Modulation for MRI Contrast Encoding
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Solution Overview
Problem
Current MRI techniques, such as Fast Spin-Echo (FSE) and Spoiled Gradient Echo (SGRE), are inefficient for acquiring both T1-weighted and T2-weighted images, especially in 3D acquisitions, requiring long scan times and compromising contrast quality due to the need for multiple acquisitions and susceptibility to magnetic field inhomogeneities.
Innovation Solution
A modified Gradient Echo (GRE) pulse sequence with RF phase modulation allows for the simultaneous acquisition of T1-weighted and T2-weighted datasets by encoding longitudinal and transverse relaxation information into the real and imaginary components of the MR signal, enabling the generation of distinct contrast-weighted images from a single pulse sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate acquisitions are performed to obtain both T1w and T2w images, then complete contrast information is acquired, but scan time is substantially increased
Solution Approach 1:
The patent combines multiple contrast mechanisms (T1w and T2w) into a single acquisition by using a gradient echo pulse sequence with RF phase modulation. The real and imaginary components of the complex MR signal are used to separately encode T2w and T1w information, respectively, allowing both contrast types to be obtained simultaneously from one scan rather than requiring separate acquisitions.
Solution Approach 2:
The gradient echo pulse sequence with RF phase modulation serves multiple functions: it simultaneously encodes both T1-weighted and T2-weighted contrast information within a single acquisition framework. The sequence is designed to extract different contrast mechanisms from the same data set, making the imaging system more versatile and efficient.
2Volume of moving object
If FSE-based 3D acquisitions are performed, then 3D imaging capability is achieved, but T1 and T2 contrast quality is compromised due to extended echo trains
Solution Approach 1:
The patent replaces the Fast Spin Echo (FSE) pulse sequence mechanism with a gradient echo pulse sequence mechanism that uses RF phase modulation. This substitution allows 3D imaging to be achieved without relying on extended echo trains, thereby preserving both T1 and T2 contrast quality while maintaining volumetric imaging capability.
3Loss of information
If patients undergo long scan times, then comprehensive imaging data is collected, but patient movement and tolerance are compromised
Solution Approach 1:
By merging multiple contrast acquisitions into a single scan using RF phase modulated gradient echo sequences, the patent reduces the overall scan time required to collect comprehensive imaging data. This eliminates the need for patients to remain stationary for extended periods while still obtaining complete T1w and T2w contrast information.
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 reduces scan time significantly, allowing for efficient acquisition of high-quality T1w and T2w images in a single acquisition, overcoming the limitations of traditional methods by providing separable and distinct contrast weightings, thus improving clinical efficiency and patient tolerance.
Implementation Method 1
If the substance, or tissue, is subjected to a magnetic field (excitation field B1) that is in the x-y plane and that is near the Larmor frequency, the net aligned moment, Mz, may be rotated, or 'tipped', into the x-y plane to produce a net transverse magnetic moment Mxy. A signal is emitted by the excited nuclei or 'spins', after the excitation signal B1 is terminated, and this signal may be received and processed to form an image.
Implementation Method 2
When utilizing these 'MR' signals to produce images, magnetic field gradients (Gx, Gy, and Gz) are employed. Typically, the region to be imaged is scanned by a sequence of measurement cycles in which these gradients vary according to the particular localization method being used.
Implementation Method 3
The computer system is programmed to control the plurality of gradient coils and the RF system to perform a gradient echo pulse sequence that includes a phase increment of an RF pulse of the gradient echo pulse sequence selected to encode longitudinal relaxation (T1) information in an imaginary component of a magnetic resonance (MR) data received from the subject and encode at least transverse relaxation (T2) information in a real component of the MR data received from the subject.
Data Source
AI summary
A system and method are provided for producing at least one of an image or a map of a subject. The method includes controlling a magnetic resonance imaging system to perform a pulse sequence that includes at least one phase increment of an RF pulse of a gradient echo pulse sequence configured to encode longitudinal relaxation (T1) information in an imaginary component of a magnetic resonance (MR) data received from the subject and encode at least transverse relaxation (T2) information in a real component of the MR data received from the subject. The method also includes generating a T1 image or map of the subject or a T2 image or map of the subject from the MR data and displaying the T1 image or map or the T2 image or map of the subject.