Non-contrast MRA Using Region-Selective Saturation Pulse
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Solution Overview
Problem
Conventional non-contrast magnetic resonance angiography (MRA) techniques require elongated imaging times, leading to insufficient background signal suppression due to subject motion or misregistration, and fail to observe temporal changes in blood flow.
Innovation Solution
A magnetic resonance imaging apparatus that acquires multiple data sets with different delay times using a region-selective saturation pulse followed by region-non-selective inversion recovery pulses, allowing for effective suppression of background signals and visualization of blood flow changes without the need for contrast media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ASL technique is used to suppress background signal by performing subtraction between image data, then background signal suppression is achieved, but imaging time is elongated
Solution Approach 1:
The patent applies a saturation pulse to selectively saturate blood signal in a predefined region before the imaging sequence. This preliminary action labels the blood vessels in advance, allowing the subsequent imaging to capture only the labeled blood flow without requiring time-consuming subtraction between multiple images. The saturation pulse is applied once before imaging, and the labeled blood flow is then visualized directly.
2Reliability
If imaging time is elongated to suppress background signal, then background signal suppression improves, but subject motion or misregistration occurs
Solution Approach 1:
By applying the saturation pulse before the imaging sequence, the blood vessels are labeled in advance. This allows the imaging to capture labeled blood flow directly without requiring multiple sequential images that would be prone to motion artifacts. The preliminary labeling action eliminates the need for time-consuming image subtraction and reduces susceptibility to subject motion during the imaging process.
3Reliability
If conventional ASL technique is used, then background signal suppression is achieved, but temporal change of blood cannot be observed
Solution Approach 1:
The saturation pulse is applied before the imaging sequence to label blood vessels, enabling the visualization of blood flow dynamics over time. By establishing the labeled blood flow state in advance, the system can capture temporal changes in blood flow patterns during the imaging process, allowing observation of hemodynamic variations without requiring complex multi-image subtraction procedures.
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
Enables the acquisition of non-contrast MRA images with sufficient background signal suppression in shorter times and the ability to observe temporal blood flow changes, reducing imaging time and eliminating the need for subtraction images.
Implementation Method 1
a region-selective saturation pulse is first applied
Implementation Method 2
a region-non-selective inversion recovery pulse is then applied
Implementation Method 3
the delay time being defined as a period from a time of application of the saturation pulse to a time of start of acquisition of the magnetic resonance data
Data Source
AI summary
A magnetic resonance imaging (MRI) apparatus acquires magnetic resonance (MR) data associated with a plurality of different delay times according to a pulse sequence in which a region-selective saturation pulse is first applied, a region-non-selective inversion recovery pulse is then applied, and then the magnetic resonance data is acquired, the delay time being defined as a period from the saturation pulse application time to the start of MR data acquisition. A plurality of blood flow image data respectively associated with the plurality of different delay times are created using the acquired MR data.