Variable Slice Sequence for Uniform Fat Saturation in MR
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Solution Overview
Problem
In respiration-triggered multi-shot magnetic resonance acquisitions, uneven fat saturation occurs across slices due to the cyclical nature of fat saturation techniques, leading to inconsistent image quality, especially when the acquisition time window is limited, resulting in some slices having insufficient fat saturation.
Innovation Solution
Varying the sequence of slices within acquisition blocks and adjusting the sequence of k-space portions to ensure that slices are equally affected by fat saturation, with the k-space center being acquired later in the sequence to maximize fat saturation levels across all slices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fat saturation technique is applied in triggered multi-shot acquisitions with fixed slice sequence, then acquisition can be completed within respiration time window, but uneven fat saturation occurs across slices leading to inconsistent image quality
Solution Approach 1:
The patent applies dynamics by making the slice acquisition sequence variable rather than fixed. The control device dynamically adjusts the slice sequence in each acquisition block based on a predetermined pattern, ensuring that slices are acquired in different orders across multiple blocks. This dynamic reordering allows all slices to receive adequate fat saturation pulses while completing acquisition within the respiration-triggered time window, thereby resolving the contradiction between acquisition speed and fat saturation uniformity.
2Reliability
If multiple fat saturation pulses are applied to achieve sufficient saturation, then fat saturation level increases, but acquisition time increases and may exceed available time window
Solution Approach 1:
The patent applies preliminary action by distributing fat saturation pulses across multiple acquisition blocks in advance. Instead of concentrating all saturation pulses in one block, the system preliminarily applies saturation pulses to different slices in each block according to a predetermined sequence pattern. This allows sufficient fat saturation to be achieved across all slices while spreading the time consumption across multiple blocks, preventing any single block from exceeding the respiration time window.
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 achieves uniform fat saturation across all slices, improving image quality by ensuring that each slice is subjected to sufficient fat saturation, thereby eliminating images with insufficient fat saturation and enhancing overall image homogeneity.
Implementation Method 1
For the acquisition of magnetic resonance signals, it is known upon receiving a trigger signal relating to the patient's respiration and indicating the start of an acquisition time window, to begin a fat saturation technique and, to acquire magnetic resonance signals for the different slices
Implementation Method 2
Various fat saturation techniques are therefore known in which, for example, a fat saturation pulse is emitted at regular intervals as a radiofrequency (RF) pulse
Implementation Method 3
Magnetic resonance imaging is well established as a clinical imaging method
Data Source
AI summary
In a method and magnetic resonance (MR) scanner for acquiring an MR data set of multiple slices of a volume of interest of an examination object (patient), on receipt of a trigger signal relating to the patient's respiration and indicating the start of an acquisition time window, a fat saturation technique is begun and, in one of a number of acquisition blocks having a number of echo trains each relating to a single slice and a single portion of k-space, wherein all the echo trains of each individual acquisition block relate to different slices, magnetic resonance data for the different slices are acquired. A magnetic resonance image of each slice is determined for that slice by combining magnetic resonance data acquired in different acquisition blocks and relating to a portion of k-space. For at least two of the acquisition blocks, a different sequence of the slices to be acquired by the echo trains is used within the acquisition block.