MR Imaging Contrast Control via KWIC Filtering
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Solution Overview
Problem
Current MR imaging techniques using long echo trains suffer from contrast contamination, which hampers the achievement of desired image contrast in clinical diagnostics.
Innovation Solution
A method involving a multi-echo imaging sequence with varied relaxation time weightings and k-space weighted image contrast filtering to acquire and reconstruct MR images with controlled contrast, utilizing techniques like KWIC filtering and compressed sensing to reduce contamination and enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If long echo trains are used in MR imaging, then acquisition speed is improved, but contrast contamination occurs
Solution Approach 1:
The k-space data is segmented into multiple slices along the slice direction, with each slice acquired at different time points during the echo train. This segmentation allows selective filtering of data from different slices to remove contrast contamination while preserving acquisition speed benefits
Solution Approach 2:
The harmful contrast-contaminated components are extracted and removed from the k-space data by selectively filtering out data from specific slices that contain unwanted contrast information, while retaining clean data from other slices for image reconstruction
2Stability of the object's composition
If standard Cartesian phase-encoding is used in stack-of-stars acquisition, then data consistency is improved, but motion artifacts increase
Solution Approach 1:
Different encoding strategies are applied to different directions: Cartesian phase-encoding is used along the slice direction to maintain data consistency, while radial encoding is used in the in-plane directions to provide motion robustness and reduce motion artifacts
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
Enables the reconstruction of MR images with desired contrast by varying relaxation time weightings and employing advanced filtering techniques, reducing unwanted contrast contamination and improving image clarity.
Implementation Method 1
the body of the patient to be examined is arranged in a strong, uniform magnetic field B0
Implementation Method 2
application of an electromagnetic alternating field (RF field) of defined frequency (so-called Larmor frequency, or MR frequency)
Implementation Method 3
time-varying magnetic field gradients extending along the three main axes are superposed on the uniform magnetic field B0
Data Source
Figure 1
Figure 2~4
AI summary
The invention relates to a method of MR imaging of an object. It is an object of the invention to enable MR imaging using the stack-of-stars acquisition scheme with an enhanced control of the contrast of the reconstructed MR image. The method of the invention comprises the steps of: a) generating MR signals by subjecting the object (10) to a number of shots of a multi-echo imaging sequence comprising RF pulses and switched magnetic field gradients, wherein a train of echo signals is generated by each shot; b) acquiring the echo signals according to a stack-of-stars (i.e. a hybrid radial 3D acquisition scheme wherein radial sampling is performed in each slice plane and phase encoding is performed along the slice encoding direction) or stack-of-spirals scheme, wherein the echo signals are acquired as radial or spiral k-space profiles (Sl-S12) arranged at different positions along a slice direction in k-space, wherein echo signals from different k-space slices are acquired in each shot of the imaging sequence and wherein the echo signals are acquired from each k-space slice with different relaxation time weightings; and c) reconstructing at least one MR image of a desired contrast from the acquired echo signals using a k-space weighted image contrast (KWIC) filter. Moreover, the invention relates to a MR device (1) and to a computer program for a MR device (1).