MRI Apparatus RF Pulse Timing for Non-Contrast MRA Contrast
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Solution Overview
Problem
Non-contrast magnetic resonance angiography (MRA) faces challenges in acquiring sufficient images due to poor contrast between peripheral blood vessels and background tissue, as existing methods struggle to effectively separate and visualize blood vessels without contrast agents.
Innovation Solution
The magnetic resonance imaging apparatus independently sets the timing for non-selective and selective inversion pulses to control the longitudinal magnetization components of background tissue and blood, ensuring that the blood reaches the desired position in the imaging region while the background tissue's magnetization is at zero, thereby enhancing contrast and imaging power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-contrast MRA is performed with conventional timing of RF pulses, then the imaging process is simpler, but the contrast between peripheral blood vessels and background tissue is insufficient
Solution Approach 1:
The patent divides the imaging process into two distinct timing phases: a first time for non-selective RF pulse irradiation to suppress background tissue magnetization, and a second time for selective RF pulse irradiation to label blood in specific vessels. This segmentation allows independent optimization of background suppression and blood vessel enhancement, resolving the contradiction between simplicity and contrast quality.
Solution Approach 2:
The patent applies preliminary action by first irradiating a non-selective RF pulse to suppress the longitudinal magnetization of background tissue before acquiring the angiographic image. This preliminary suppression of background signal prepares the imaging conditions for enhanced blood vessel visibility, achieving high contrast without requiring contrast agents.
2Measurement precision
If timing of RF pulses is optimized for blood vessel imaging, then contrast is improved, but the imaging sequence becomes more complex
Solution Approach 1:
The patent employs periodic action through a repeating pulse sequence that alternates between non-selective RF pulse irradiation phases and selective RF pulse irradiation phases. This periodic structure maintains consistent background suppression while periodically enhancing blood vessel signals, achieving high contrast imaging through a systematic yet manageable sequence complexity.
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 improves the imaging power by effectively separating blood vessels from background tissue, allowing for better visualization of peripheral blood vessels and maintaining sufficient contrast, thus enhancing the quality of non-contrast imaging.
Implementation Method 1
Magnetic resonance imaging is an imaging method in which the spins of atomic nuclei of a subject placed in a static magnetic field are magnetically excited with radio frequency (RF) pulses with the Larmor frequency, thereby generating an image from the data of magnetic resonance signals generated, accompanied by the excitation.
Implementation Method 2
Magnetic resonance imaging is an imaging method in which the spins of atomic nuclei of a subject placed in a static magnetic field are magnetically excited with radio frequency (RF) pulses with the Larmor frequency
Data Source
AI summary
A magnetic resonance imaging apparatus according to an embodiment includes sequence controlling circuitry and image generating circuitry. The sequence controlling circuitry acquires magnetic resonance signals in an imaging region. The image generating circuitry generates an image. The sequence controlling circuitry sets timings of RF pulses such that a first time and a second time are different. Here, the first time is a time since an irradiation of a first RF pulse without selection of region until a start of acquisition. The second time is a time since an irradiation of a second RF pulse with selection of the labeling region until the start of acquisition. The second time is also a time for a liquid present in the labeling region to reach a desired position in the imaging region. The first time is also a time for longitudinal magnetization components of a background tissue to become substantially zero.