MR Contrast Preparation With Immediate K-Space Center Sampling
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Solution Overview
Problem
Existing MR imaging techniques, such as SPIR and SPAIR, face inefficiencies due to dead times in dynamic imaging, which impact temporal resolution and efficiency, particularly in fat suppression and contrast-enhanced MR imaging.
Innovation Solution
A method that involves a contrast preparation sequence followed by immediate k-space sampling, including a central portion during a first time interval coinciding with a desired nuclear magnetization state, and subsequent sampling of peripheral portions, minimizing dead times and enhancing contrast-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a contrast preparation sequence with inversion RF pulse is applied to suppress fat signals, then fat suppression and contrast enhancement are improved, but dead times increase and temporal resolution deteriorates
Solution Approach 1:
The patent applies a contrast preparation sequence with inversion RF pulse before the imaging sequence to manipulate nuclear magnetization states. This preliminary action creates the desired contrast conditions (fat suppression, tissue differentiation) before signal acquisition begins, allowing optimal contrast-to-noise ratio while minimizing dead time by preparing the magnetization state in advance of the actual imaging.
Solution Approach 2:
The patent dynamically adjusts the timing of k-space sampling relative to the inversion RF pulse and magnetization recovery process. By making the sampling timing adaptive and flexible rather than fixed, the system can optimize the balance between allowing sufficient magnetization recovery for contrast enhancement while minimizing dead time and maintaining temporal resolution for dynamic imaging applications.
2Measurement precision
If inversion RF pulse is applied to fully invert fat magnetization, then fat suppression is improved, but temporal resolution and acquisition speed are reduced
Solution Approach 1:
The inversion RF pulse is applied as a preliminary action before the imaging sequence to fully invert fat magnetization. This allows the fat suppression to be established in advance, and subsequent k-space sampling can proceed at optimized speeds without compromising the fat suppression effect, as the magnetization state is already prepared.
Solution Approach 2:
The patent segments the imaging process into distinct phases: contrast preparation (inversion RF pulse), magnetization recovery period, and signal acquisition (k-space sampling). This segmentation allows each phase to be optimized independently - the inversion pulse for fat suppression, the recovery period for magnetization stabilization, and the sampling phase for maximum speed and temporal resolution.
3Measurement precision
If k-space sampling is delayed to allow magnetization recovery, then contrast quality is improved, but temporal resolution deteriorates
Solution Approach 1:
The contrast preparation sequence is executed as a preliminary action immediately before k-space sampling. This preliminary magnetization manipulation ensures that the desired contrast states are established before signal acquisition begins, eliminating the need to delay sampling for contrast optimization and thereby preserving temporal resolution.
Solution Approach 2:
The patent maintains continuous useful action by making the imaging sequence start directly after the preparation sequence without idle dead time. The k-space sampling begins immediately as the magnetization is in the desired state, ensuring continuous productive operation while maintaining optimal contrast quality through proper timing of the preparation and sampling phases.
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 faster acquisition, higher temporal resolution, and improved contrast-to-noise ratio in MR images, reducing the impact of nuclear magnetization recovery on image quality.
Implementation Method 1
subjecting the object to a contrast preparation sequence comprising at least one preparation RF pulse to non-selectively or selectively, partially or completely manipulate nuclear magnetization
Implementation Method 2
subjecting the object to an imaging sequence comprising at least one excitation RF pulse and switched magnetic field gradients to generate MR signals
Implementation Method 3
applying a spectrally selective inversion radiofrequency (RF) pulse that is specifically tuned to the resonance frequency of fat protons
Data Source
Figure 1
Figure 2A
Figure 2B~3
AI summary
The invention discloses a method of imaging an object (10) placed in a magnetic field, comprising: subjecting the object (10) to a contrast preparation sequence (PRE) comprising at least one preparation radiofrequency, RF, pulse to non-selectively or selectively, partially or completely manipulate nuclear magnetization; subjecting the object (10) to an imaging sequence (IM) comprising at least one excitation RF pulse and switched magnetic field gradients to generate magnetic resonance, MR, signals, wherein the imaging sequence (IM) starts directly after the preparation sequence (PRE) and samples a central portion of k-space (C) during a first time interval (TI1) encompassing a target time point at which the nuclear magnetization assumes a desired state after the contrast preparation sequence (PRE), and subsequently samples peripheral portions (PN, PP) of k-space during a second time interval (TI2); acquiring the MR signals from the object (10); and reconstructing an MR image from the acquired MR signals, wherein the visibility of particular tissues, structures, or pathological conditions within the object (10) is enhanced in the MR image by the contrast preparation sequence (PRE). A system is further disclosed, comprising a computational system configured to perform the method.