MRI Apparatus Inversion Pulse Sequence for Slow Blood Flow Imaging
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Solution Overview
Problem
Conventional MRI techniques, such as the Time-SLIP method, struggle to effectively image slow-moving blood flows due to limitations in rendering blood flow ranges, particularly when background tissues like venous blood and stationary tissues are present.
Innovation Solution
An MRI apparatus and program that utilize a series of inversion pulses and carefully timed wait periods to invert and relax the longitudinal magnetization components of bodily fluids and background tissues, ensuring that the bodily fluid's magnetization exceeds the null point before data acquisition, thereby emphasizing the fluid in the MR image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional MRI techniques (Time-SLIP method) are used to image blood flow, then blood flow can be visualized, but the rendered blood flow range is narrowed when imaging patients with slow blood flow
Solution Approach 1:
The patent applies preliminary inversion pulses before data acquisition to prepare the magnetization state of blood and background tissues. By inverting the longitudinal magnetization components of both blood and background tissues before the actual imaging, the system creates optimal contrast conditions that enable accurate visualization of slow blood flow throughout the entire imaging region, resolving the contradiction between rendering range and image quality.
2Measurement precision
If inversion pulses are applied to invert longitudinal magnetization components, then contrast between bodily fluid and background tissue is enhanced, but multiple inversion pulses and wait times increase the complexity of the pulse sequence
Solution Approach 1:
The patent segments the inversion process into multiple distinct inversion pulses, each targeting specific tissue types at different timing intervals. The first inversion pulse inverts both blood and background tissue magnetization, while subsequent inversion pulses selectively invert background tissue magnetization. This segmentation allows precise control over the magnetization state of different tissues, achieving high contrast precision while organizing the complex operations into manageable sequential steps.
3Measurement precision
If multiple inversion pulses are transmitted at different wait times, then the bodily fluid's magnetization exceeds the null point before data acquisition, but the imaging time is extended
Solution Approach 1:
The patent employs periodic inversion pulses transmitted at specific wait time intervals after the initial inversion. By rhythmically inverting the magnetization of background tissues at predetermined intervals, the system creates optimal contrast conditions precisely when needed for data acquisition. This periodic action pattern ensures that blood and background tissue magnetization are in the desired states at the moment of imaging, achieving timing precision while using efficient temporal cycling to minimize total imaging time.
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 allows for the wider rendering of bodily fluids, even in cases of slow flow, by ensuring the bodily fluid's magnetization is significantly higher than the background tissue at the time of data acquisition, thus improving the visibility of arterial blood over venous blood and stationary tissues.
Implementation Method 1
a static magnetic field generating device for generating a static magnetic field to the subject so as to assign positive values to a longitudinal magnetization component of the bodily fluid and a longitudinal magnetization component of the background tissue
Implementation Method 2
a transmission coil for transmitting an RF pulse to the subject
Data Source
AI summary
An MRI apparatus for imaging a subject so as to emphasize, more than a background tissue, a bodily fluid flowing through an imaging region of the subject, the apparatus includes a transmission coil for transmitting an RF pulse to the subject, a first transmission coil control device for controlling the transmission coil so that the transmission coil transmits a first inversion pulse for inverting longitudinal magnetization components of the bodily fluid and the background tissue to negative values from the positive values, a second transmission coil control device for controlling the transmission coil so that the transmission coil transmits a second inversion pulse for inverting the longitudinal magnetization component of the background tissue to the positive value from the negative value inverted by the first inversion pulse, a third transmission coil control device for controlling the transmission coil so that the transmission coil transmits a third inversion pulse for inverting the longitudinal magnetization component of the background tissue to the negative value from the positive value inverted by the second inversion pulse and a fourth transmission coil control device for controlling the transmission coil so that the transmission coil transmits an excitation pulse for acquiring data about the bodily fluid.