MRI Apparatus Frequency-Selective Pulse Center Frequency Calculation
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Solution Overview
Problem
Magnetic resonance imaging (MRI) systems face challenges in improving image quality due to the degradation of fat suppression effects, even when center frequencies are optimized, primarily because of the frequency characteristics of fat suppression pulses.
Innovation Solution
A magnetic resonance imaging apparatus that acquires resonance frequency distributions of different tissues, calculates a center frequency for frequency-selective pulses, and applies these pulses to enhance or suppress specific tissues, thereby optimizing the fat suppression effect and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If center frequency optimization is performed for multi-slice imaging, then imaging coverage and efficiency are improved, but fat suppression effect is degraded
Solution Approach 1:
The patent divides the frequency optimization into separate processes: first optimizing center frequencies for multi-slice imaging coverage, then separately optimizing fat suppression pulse frequencies. This segmentation allows each function to be optimized independently without compromising the other, resolving the contradiction between imaging efficiency and fat suppression effect.
Solution Approach 2:
The patent performs preliminary static magnetic field shimming and center frequency optimization before applying the frequency-selective fat suppression pulse. By preparing the magnetic field distribution and frequency parameters in advance, the system achieves both efficient multi-slice imaging and effective fat suppression without frequency conflicts.
2Reliability
If frequency-selective pulse is applied to suppress fat, then fat suppression effect is improved, but other tissue signals may be affected
Solution Approach 1:
The patent applies different frequency characteristics to different regions: a first frequency range for exciting target tissues and a second frequency range for suppressing fat signals. By localizing different frequency treatments to different tissue types, the system achieves selective fat suppression while preserving other tissue signals.
Solution Approach 2:
The patent uses a frequency-selective pulse as an intermediary mechanism that selectively interacts with fat protons based on their resonant frequency. This intermediary approach allows targeted fat suppression without directly affecting other tissue signals, as the pulse frequency is precisely tuned to match only the fat resonance characteristics.
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 precise suppression or emphasis of specific tissues, enhancing the fat suppression effect and improving the overall quality of magnetic resonance images by accurately determining the center frequency for frequency-selective pulses based on tissue resonance frequencies.
Implementation Method 1
a magnetic resonance imaging (MRI) apparatus that performs shimming on a static magnetic field based on a static magnetic field distribution
Data Source
AI summary
According to one embodiment, a magnetic resonance imaging apparatus includes processing circuitry. The processing circuitry acquires a first resonance frequency distribution of a first tissue and a second resonance frequency distribution of a second tissue which is different from the first tissue. The processing circuitry calculates a center frequency of a frequency-selective pulse that suppresses or emphasizes either one of the first tissue and the second tissue in accordance with the first and second resonance frequency distributions. The processing circuitry collects a magnetic resonance signal after the frequency-selective pulse is applied at the calculated center frequency.