Background Suppression in Time-of-Flight MRA via Dual Saturation
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Solution Overview
Problem
Current methods for background suppression in time-of-flight (TOF) magnetic resonance angiography (MRA) are inefficient, often requiring manual intervention, prolonging scan times, and being sensitive to B0 and B1 inhomogeneity, which limits vessel-to-background contrast and complicates pulse sequence design.
Innovation Solution
A method involving high-resolution and low-resolution TOF acquisitions with saturation bands to generate a subtraction image, where the second TOF image with two saturation bands on both sides of the imaging slab is used to cancel out static tissue signals, reducing scan time and eliminating the need for additional fat saturation or magnetization transfer pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fat saturation and magnetization transfer are used to suppress background signals, then vessel-to-background contrast is improved, but pulse sequence design becomes complicated and scan time is prolonged
Solution Approach 1:
The patent applies segmentation by dividing the saturation strategy into two distinct parts: (1) a first TOF image acquired with a saturation band on one side only, and (2) a second TOF image acquired with saturation bands on both sides. By segmenting the saturation application and subsequently subtracting the images, the method achieves background suppression without requiring complex fat saturation or magnetization transfer pulse sequences.
Solution Approach 2:
The patent changes the parameter of saturation band configuration between two acquisitions. The first acquisition uses a single saturation band while the second uses dual saturation bands. This parameter change in the saturation configuration, combined with image subtraction, enables background signal suppression while maintaining a relatively simple pulse sequence design.
2Manufacturing precision
If fat saturation and magnetization transfer are used to suppress background signals, then vessel-to-background contrast is improved, but scan time is prolonged
Solution Approach 1:
The patent segments the background suppression task into two separate TOF acquisitions with different saturation configurations rather than using a single prolonged acquisition with complex fat saturation or magnetization transfer pulses. This segmentation allows for more efficient use of scan time while achieving the desired contrast improvement.
Solution Approach 2:
By changing the saturation band configuration parameter between two relatively quick acquisitions instead of using time-consuming fat saturation or magnetization transfer sequences, the patent reduces overall scan time while maintaining effective background suppression.
3Manufacturing precision
If manual region restriction is applied to exclude fat-containing layers, then vessel-to-background contrast is improved, but operation time is increased
Solution Approach 1:
The patent performs preliminary background suppression through dual saturation band acquisition before MIP reconstruction. By pre-suppressing the background signals in the acquired images through the subtraction method, the need for manual region restriction operations is eliminated, thereby improving contrast without increasing operation time.
Solution Approach 2:
The subtraction of the two TOF images with different saturation configurations automatically suppresses background signals without requiring manual intervention. The system performs the background suppression task itself through image processing rather than requiring user-driven region restriction.
4Manufacturing precision
If dual saturation bands are applied in low-resolution acquisition, then background suppression is achieved, but image resolution is reduced
Solution Approach 1:
The patent segments the imaging task into two acquisitions with different resolutions and saturation configurations. The low-resolution dual-saturation image is used specifically for background suppression purposes, while the final high-quality MIP reconstruction is derived from the high-resolution single-saturation image. This segmentation allows each acquisition to be optimized for its specific purpose.
Solution Approach 2:
The low-resolution dual-saturation TOF image serves as an intermediary that provides background suppression information. This intermediary image is subtracted from the high-resolution image to remove background signals, while the final high-resolution MIP image is reconstructed only from the high-resolution acquisition data, thus maintaining image quality.
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 background signals, improving vessel-to-background contrast without extending scan time significantly, allowing direct maximum intensity projection (MIP) on the subtraction image, thus enhancing visualization of small vessels.
Implementation Method 1
obtaining a first TOF image through a high-resolution acquisition with a saturation band on one side of an imaging slab, obtaining a second TOF image through a low-resolution acquisition with two saturation bands on both sides of the imaging slab
Implementation Method 2
MRA uses the inherent motion sensitivity of MRI to produce images of vascular structures. Magnetic resonance (MR) angiograms are acquired by exciting nuclei in a selected volume of interest and detecting the signal contrast between moving nuclei and stationary nuclei within that volume
Implementation Method 3
TOF is the most widely used MRA for imaging head and neck vasculature, which relies on inflow replenishment to create contrast between flowing blood and stationary tissue
Data Source
AI summary
Systems and methods for suppressing background in time-of-flight (TOF) magnetic resonance angiography (MRA) are disclosed. An exemplary method includes obtaining a first TOF image through a high-resolution acquisition with a saturation band on one side of an imaging slab, obtaining a second TOF image through a low-resolution acquisition with two saturation bands on both sides of the imaging slab, and subtracting the second TOF image from the first TOF image to obtaining a subtraction TOF image. Post processing such as maximum intensity projection (MIP) is performed on the subtraction TOF image.