Time-Resolved MRI via K-Space Undersampling and Iterative Reconstruction
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Solution Overview
Problem
Current magnetic resonance imaging (MRI) techniques face limitations in generating time-resolved images of cyclical movements, such as heartbeats, due to constraints in spatial and temporal resolution, which restrict the acquisition of multiple cycle periods within a breath-hold time, leading to reduced information content and patient comfort issues.
Innovation Solution
A method utilizing undersampling of the k-space during magnetic resonance signal acquisition, combined with iterative reconstruction and pseudo-random scanning, allows for the generation of time-resolved images by applying spatial magnetization patterns at different tagging time instants within a cycle, enabling increased spatial and temporal resolution and improved contrast-to-noise ratio, while shortening measurement time and accommodating multiple cycles within a single breath-hold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional segmented CINE measurements are used to obtain time-resolved images, then spatial and temporal resolution requirements can be met, but the measurement time exceeds a single breath-hold duration and information content is reduced
Solution Approach 1:
The patent applies partial sampling in the k-space domain by acquiring only a subset of k-space lines (e.g., every nth line) rather than the complete k-space. This partial action reduces the number of required measurements and shortens acquisition time while iterative reconstruction algorithms compensate for the missing data to maintain image quality and resolution
Solution Approach 2:
The patent changes the sampling parameter by using non-uniform or accelerated k-space sampling patterns instead of conventional uniform sampling. By modifying the sampling rate and pattern (e.g., using radial, spiral, or compressed sensing patterns), the measurement time is reduced while maintaining the ability to reconstruct high-quality time-resolved images through advanced reconstruction techniques
2Loss of information
If multiple cycle periods are acquired within a breath-hold time, then more information content is obtained, but the measurement time increases and patient comfort deteriorates
Solution Approach 1:
The patent acquires partial k-space data for multiple cardiac cycles instead of complete k-space for fewer cycles. This partial sampling approach enables the accumulation of information from multiple cycles (improving information content) while keeping the total acquisition time within a single breath-hold (maintaining patient comfort)
Solution Approach 2:
The patent segments the k-space acquisition across multiple cardiac cycles, where different portions of k-space are sampled during different cycles. This segmentation allows efficient utilization of the available breath-hold time to gather information from multiple cycles without requiring the patient to hold their breath for an excessively long continuous period
3Productivity
If k-space is undersampled to shorten measurement time, then acquisition speed increases, but image quality and signal-to-noise ratio may deteriorate
Solution Approach 1:
The patent employs iterative reconstruction algorithms that use feedback loops to progressively refine the image reconstruction from undersampled k-space data. The reconstruction process incorporates constraints and prior knowledge, continuously adjusting the solution to maximize image quality and signal-to-noise ratio while respecting the limited acquired data
Solution Approach 2:
The patent introduces iterative reconstruction algorithms as an intermediary processing step between the undersampled k-space acquisition and the final image output. This intermediary computation compensates for the information loss from undersampling by applying regularization, denoising, and reconstruction techniques that restore image quality and signal-to-noise ratio
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 enhances the spatial and temporal resolution of CINE measurements, increases information content, and improves patient comfort by completing the examination within a shorter breath-hold time, maintaining signal quality and allowing for precise evaluation of myocardial function.
Implementation Method 1
Magnetic resonance tomography (MRT) or magnetic resonance imaging (MRI) is an imaging method used in medical diagnostics
Implementation Method 2
rapidly switching gradient fields generated by a gradient system of the magnetic resonance device may overlay a static basic magnetic field
Implementation Method 3
a radio frequency antenna unit of the magnetic resonance device serves to radiate RF pulses into the examination object in order to trigger magnetic resonance signals
Data Source
AI summary
The embodiments disclosed herein relate to a method for generating time-resolved images of an examination object, which executes a cyclical movement, and to a magnetic resonance device, and a computer program product herefor. According to a first aspect, at least one spatial magnetization pattern with spatial magnetization differences is generated during a magnetization of the examination object. Furthermore, magnetic resonance signals of the examination object are acquired after generating the spatial magnetization pattern throughout at least one cycle of the cyclical movement. At least one k-space is undersampled here during the acquisition of the magnetic resonance signals. Time-resolved images are generated based on the acquired magnetic resonance signals.