RF Intermediate Pulse for MRI Fat Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional MRI techniques face challenges in achieving adequate fat suppression and controlling image contrast, especially under high magnetic fields, where RF pulse inhomogeneity leads to inadequate fat suppression and increased imaging time, particularly in multi-slice imaging.
Innovation Solution
The implementation of a magnetic resonance imaging apparatus and method that utilizes RF intermediate pulses in conjunction with RF pre-pulses to control image contrast, allowing for more effective fat suppression and reduced imaging time by applying frequency-selective or slice-selective pulses at strategic points within the imaging sequence, such as between refocus pulses, and using spoiler gradients to suppress unwanted signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a frequency-selective fat saturation pulse is applied as a RF pre-pulse prior to FSE sequence, then fat suppression is achieved, but imaging time is increased and number of slices is reduced
Solution Approach 1:
The patent applies a frequency-selective fat saturation pulse as a RF pre-pulse before the FSE imaging sequence to preliminarily suppress fat signals. This preliminary action ensures fat suppression is achieved before imaging begins, resolving the contradiction by accepting the time cost upfront to enable faster subsequent imaging.
Solution Approach 2:
The patent segments the fat suppression function by applying multiple refocus pulses with specific flip angles (e.g., 180 degrees) at defined intervals (ETS/2) during the FSE sequence. This segmentation allows the imaging sequence to be divided into segments that collectively achieve both fat suppression and efficient imaging.
2Manufacturing precision
If multiple refocus pulses are applied at ETS intervals with specific flip angles, then image contrast control is improved, but sequence complexity increases
Solution Approach 1:
The patent employs periodic refocus pulses applied at regular ETS (Echo Train Space) intervals throughout the FSE sequence. Each refocus pulse has a consistent flip angle (typically 180 degrees) and timing pattern, creating a periodic structure that systematically controls image contrast while maintaining sequence organization and manageability.
Solution Approach 2:
The patent controls image contrast by precisely adjusting parameters of the refocus pulses, including flip angle (set to 180 degrees), timing (ETS/2 intervals), and phase encoding gradients. These parameter changes enable fine-tuned contrast control without requiring fundamentally complex sequence structures.
3Manufacturing precision
If a RF pre-pulse is applied for contrast control, then image contrast is improved, but minimum TR is increased
Solution Approach 1:
The patent applies the fat saturation pulse as a RF pre-pulse before the imaging sequence begins, performing the contrast control action preliminarily. This allows the main imaging sequence to proceed with shorter TR intervals since the contrast-modifying pre-pulse is already complete, effectively separating the contrast control timing from the imaging acquisition timing.
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 enables satisfactory control of image contrast while shortening the imaging period, allowing for increased number of slices in multi-slice imaging and improved fat suppression, even in high magnetic fields, by strategically placing RF intermediate pulses and spoiler gradients within the imaging sequence.
Implementation Method 1
excites nuclear spin of an object set in a static magnetic field with a RF signal having the Larmor frequency magnetically and reconstruct an image based on NMR signals generated due to the excitation
Implementation Method 2
an α° frequency-selective fat saturation pulse RFc1 for suppressing unnecessary signals from fat is applied as a RF pre-pulse
Implementation Method 3
a spoiler gradient magnetic field Gsp1 is applied in a gradient magnetic field direction for slice selection subsequently to the α° frequency-selective fat saturation pulse RFc1
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A magnetic resonance imaging apparatus includes a data acquisition unit and an image data generating unit. The data acquisition unit acquires MR signals for imaging by an imaging scan with applying a frequency-selective or slice-selective radio frequency intermediate pulse for controlling a contrast and a spoiler gradient magnetic field for suppressing unnecessary signal component after applying al least one of radio frequency excitation pulses. The image data generating unit generates image data based on the magnetic resonance signals.