DENSE MRI Blood Signal Suppression via Double Inversion Recovery
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Solution Overview
Problem
Conventional magnetic resonance imaging (MRI) techniques, such as cine DENSE, face challenges in suppressing residual blood signal in early cardiac phases, which interferes with accurate quantitative assessment of tissue displacement and related biomarker parameters like strain, twist, and torsion, due to blood signal presence within the imaging plane.
Innovation Solution
A method and system employing a residual blood signal suppression sequence involving inversion recovery pulses, displacement encoding, and readout modules to generate DENSE images with blood suppression, utilizing double inversion recovery pulses and navigator gating to achieve a dark-blood appearance throughout the cardiac cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional cine DENSE imaging is used, then tissue displacement information can be obtained, but residual blood signal interferes with accurate measurement in early cardiac phases
Solution Approach 1:
The patent applies inversion recovery pulses before the displacement encoding module to pre-suppress blood signal. By inverting the magnetization of blood early in the sequence and selecting an appropriate inversion time, the blood signal is nulled before it can interfere with the displacement encoding and readout processes, thereby improving measurement precision without sacrificing tissue signal.
Solution Approach 2:
The patent introduces an intermediary inversion recovery module between the excitation and the displacement encoding. This intermediary step selectively suppresses blood signal while preserving tissue signal, acting as a mediator that separates the harmful blood signal from the useful tissue displacement information without directly affecting the encoding process.
2Object-affected harmful factors
If inversion recovery pulses are applied to suppress blood signal, then blood suppression is achieved, but the sequence complexity increases
Solution Approach 1:
The patent combines the inversion recovery blood suppression module with the existing cine DENSE sequence framework. By integrating the blood suppression functionality into the established displacement encoding and readout structure, the patent achieves blood suppression without requiring a completely new sequence design, thereby limiting the increase in complexity.
Solution Approach 2:
The inversion recovery module serves multiple functions: it suppresses blood signal, preserves tissue signal through appropriate timing, and is compatible with the cine DENSE acquisition framework. This multi-functionality reduces the need for separate dedicated blood suppression sequences, thereby limiting complexity increase.
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 effectively suppresses residual blood signal in early cardiac phases, allowing for accurate and quantitative assessment of tissue displacement and biomarker parameters, enhancing image clarity and reducing errors in myocardial and vessel wall mechanics analysis.
Implementation Method 1
inversion recovery pulses after an electrocardiogram (ECG) trigger at a beginning point of a repetition time period, to obtain a magnetization-inverted slice of the tissue; the inversion time is selected to allow for a blood signal within the imaging slice of tissue to have a zero magnetization level at the inversion time
Implementation Method 2
a displacement encoding module at an inversion time during the repetition time period to apply a labelling process on the tissue and excite an imaging slice of tissue thinner than the magnetization-inverted slice
Implementation Method 3
a readout module comprised of a plurality of frames during a remainder of the repetition time period, to apply an un-labelling process on the imaging slice of tissue, thereby generating DENSE images of tissue with blood suppression within the imaging slice of tissue
Data Source
AI summary
Embodiments relate to acquiring magnetic resonance (MR) images with suppressed residual blood signal in the early cardiac phases, leading to images with a preferred dark-blood appearance throughout the entire cardiac cycle, which improves accuracy of subsequent post-processing algorithms. The acquisition of the desired blood suppressed tissue images is achieved through a double inversion recovery pulse in DENSE sequences. The double inversion recovery pulse is applied after an electrocardiogram (ECG) trigger at a beginning point of a repetition time period, followed by a displacement encoding module at an inversion time during the repetition time period and a readout module comprised of a plurality of frames during a remainder of the repetition time period. The displacement encoding module applies a labelling process on the tissue, while the readout module applies an un-labelling process. The readout module comprises an imaging sequence adapted to acquire DENSE images.