MRI Fat Suppression Using Adjustable Dummy Pulses
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Solution Overview
Problem
Current magnetic resonance imaging (MRI) fat suppression methods either result in uneven fat suppression due to spatial variations in the magnetic field, leading to reduced signal-to-noise ratio (SNR) or overly suppress fat, making it difficult to identify tumor signals in images, especially in breast imaging where mammary gland signals are abundant.
Innovation Solution
A magnetic resonance imaging apparatus with a pulse sequence that includes a pre-pulse for fat suppression and a pulse train for data acquisition, featuring adjustable dummy pulses and delay times, allowing for customizable fat suppression to achieve optimal signal recovery and suppression levels, thereby enhancing image diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If frequency selective fat suppression methods (CHESS or SPIR) are used, then fat signal suppression is achieved, but uneven suppression occurs due to spatial variations in magnetic field leading to reduced SNR
Solution Approach 1:
The patent applies a non-selective 180-degree inversion pulse instead of frequency-selective pulses, fundamentally changing the approach from frequency-based to time-based (T1 relaxation) fat suppression. This parameter change eliminates dependence on magnetic field uniformity and resonance frequency selectivity, thereby resolving the contradiction between achieving fat suppression and maintaining suppression uniformity across spatial variations.
2Object-generated harmful factors
If strong fat suppression is applied to eliminate fat signals, then fat signal reduction is achieved, but tumor signals become difficult to identify due to over-suppression
Solution Approach 1:
The patent introduces adjustable dummy pulses between the inversion pulse and data acquisition, creating a dynamic system where the suppression level can be tuned. By varying the number and timing of dummy pulses, the fat signal recovery can be controlled to achieve optimal suppression without completely eliminating all signals, thereby preserving tumor visibility while reducing fat interference.
Solution Approach 2:
The patent applies a 180-degree inversion pulse as a preliminary action before data acquisition to suppress fat signals. This preliminary inversion allows subsequent flexible adjustment through dummy pulses, enabling optimization of the balance between fat suppression and tumor signal preservation before the actual imaging data is collected.
3Object-generated harmful factors
If inversion time is adjusted to achieve optimal fat suppression, then fat signal suppression is improved, but imaging time increases
Solution Approach 1:
The patent uses a 180-degree inversion pulse which provides strong initial fat suppression, then applies a limited number of dummy pulses (partial action) to fine-tune the suppression level. This approach achieves effective fat suppression without requiring excessively long inversion times, thereby balancing suppression effectiveness with imaging efficiency.
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 apparatus effectively adjusts fat suppression levels to prevent over-suppression, maintaining high SNR and facilitating the identification of tumor signals by allowing for tailored fat signal recovery, thus improving diagnostic clarity.
Implementation Method 1
A magnetic resonance imaging apparatus is an imaging apparatus which excites a nuclear spin of a test object put in a static magnetic field by using an RF (Radio Frequency) signal of a Larmor Frequency, and reconstructs an image from a magnetic resonance signal produced from the test object together with the excitation.
Implementation Method 2
Then, if a gradient magnetic field pulse called a spoiler pulse is applied, horizontal magnetization of fat disperses and disappears.
Implementation Method 3
A recovery rate of the vertical magnetization is determined by the vertical relaxation (T1 relaxation) of fat.
Data Source
AI summary
A magnetic resonance imaging apparatus of an embodiment has a setting unit configured to set a pulse sequence having a pre-pulse for fat suppression and a pulse train for data acquisition for acquiring echo data for image reconstruction, the pulse sequence being provided with a plurality of dummy pulses between the pre-pulse for fat suppression and the head of the pulse train for data acquisition, a data acquisition unit configured to apply an RF pulse and a gradient magnetic field pulse based on the pulse sequence set by the setting unit to a test object so as to acquire the echo data, and an image generation unit configured to reconstruct an image of the test object from the acquired echo data, wherein an application time during which the plural dummy pulses are applied or flip angles of the plural dummy pulses can be adjusted.