MRI Fat Suppression Using Segmented SPIR and CHESS Pulses
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Solution Overview
Problem
Conventional magnetic resonance imaging (MRI) methods face challenges in effectively suppressing fat signals, particularly in regions with non-uniform static magnetic fields, leading to inadequate fat saturation and reduced signal-to-noise ratio, which complicates imaging and prolongs acquisition time.
Innovation Solution
A magnetic resonance imaging apparatus and method utilizing multiple frequency-selective suppression pulses with different center frequencies and frequency bands to selectively suppress fat and silicone signals, improving fat saturation by combining pulses like SPIR and CHESS, and allowing for higher signal intensity acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-frequency selective suppression pulses (CHESS or SPIR) are used, then frequency-selective fat saturation can be achieved in regions with high magnetic field uniformity, but fat saturation becomes inadequate in regions with non-uniform static magnetic fields
Solution Approach 1:
The patent divides the suppression task into multiple frequency bands by applying multiple selective suppression pulses with different center frequencies and bandwidths. This segmentation allows each pulse to target specific fat signal components, collectively achieving comprehensive suppression across the entire fat frequency spectrum even when magnetic field uniformity varies.
Solution Approach 2:
The patent combines multiple selective suppression pulses (CHESS and SPIR) with different characteristics into a unified suppression scheme. By merging the frequency-selective advantages of CHESS with the inversion recovery capabilities of SPIR across multiple frequencies, the system achieves robust fat saturation that adapts to varying magnetic field conditions.
2Adaptability or versatility
If non-frequency selective suppression methods (STIR) are used, then suppression can be achieved across varying magnetic field uniformities, but signal-to-noise ratio decreases and imaging time increases
Solution Approach 1:
Instead of applying a single broad non-selective suppression pulse, the patent segments the suppression into multiple narrow frequency-specific pulses. This allows each pulse to be more efficient and targeted, reducing the total suppression time and preserving signal quality while achieving suppression across varying field conditions through the combined effect of multiple pulses.
3Reliability
If multiple selective suppression pulses with different frequencies are applied, then comprehensive fat saturation can be achieved, but the complexity of the suppression scheme increases
Solution Approach 1:
The patent creates a universal suppression framework where multiple selective pulses with different frequencies and characteristics (CHESS and SPIR) work together through a common control scheme. This multi-functional approach allows the same basic pulse structure to be adapted across multiple frequencies, achieving comprehensive suppression without proportionally increasing system 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
The approach enhances fat saturation efficacy, stabilizes signal suppression across varying magnetic field uniformities, reduces imaging time, and maintains consistent signal quality, offering an alternative to traditional non-frequency selective methods like STIR.
Implementation Method 1
magnetic resonance imaging (MRI) apparatus and a magnetic resonance imaging method that radio excites nuclear spins of an object magnetically with an RF (radio frequency) signal having the Larmor frequency and reconstructs an image based on an NMR (nuclear magnetic resonance) signal generated due to the excitation
Implementation Method 2
the CHESS method is a method to suppress only fat signals frequency-selectively using 3.5 ppm difference in resonant frequencies between water protons and fat protons
Implementation Method 3
the longitudinal magnetization z of the proton spins increases with time to show a plus value by longitudinal relaxation (T1 relaxation)
Data Source
AI summary
A magnetic resonance imaging (MRI) apparatus includes an MRI imaging condition setting unit configured to set an imaging condition frequency-selectively applying a first suppression pulse for suppressing fat and further frequency-selectively applying a second suppression pulse to the fat after applying the first suppression pulse, a slip angle of the second suppression pulse differing from that of the first suppression angle, and the second suppression pulse further suppressing remaining fat after applying the first suppression pulse. The image data acquisition unit acquires image data according to the imaging condition.