Time-Resolved MRA With Continuous Table Motion
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Solution Overview
Problem
Current magnetic resonance angiography (MRA) techniques face limitations in acquiring time-resolved images over extended fields of view, requiring multiple repositionings and additional contrast injections, which are costly and time-consuming, especially when imaging large anatomical regions like the lower extremity.
Innovation Solution
A method for acquiring time-resolved three-dimensional images using continuous patient table motion in an MRI system, employing a k-space undersampling pattern where the center of k-space is sampled at a higher temporal rate than peripheral k-space in radial sectors, allowing for the reconstruction of images as the subject moves through the scanner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple repositionings and additional contrast injections are used to acquire time-resolved images over extended fields of view, then complete coverage of large anatomical regions is achieved, but the procedure becomes more time-consuming and costly
Solution Approach 1:
The patient table moves continuously through the MRI scanner during the entire imaging procedure, eliminating the need to stop and reposition the table multiple times. This continuous motion allows the contrast bolus to be tracked throughout its passage through the vasculature in a single uninterrupted scan, reducing total scan time while maintaining complete field of view coverage
Solution Approach 2:
The system预先 determines the optimal table motion velocity based on the contrast injection rate and desired temporal resolution. By pre-planning and executing the continuous table movement at the correct speed, the scan captures the entire contrast bolus passage through the extended field of view in one go, avoiding the need for multiple contrast injections and repositionings
2Area of stationary object
If multiple repositionings are performed to image extended fields of view, then complete vascular coverage is achieved, but the procedure complexity increases
Solution Approach 1:
The continuous table motion eliminates the need for multiple discrete repositioning steps, contrast injections, and image registration procedures. The single continuous scan simplifies the overall procedure while maintaining complete vascular coverage through the extended field of view
Solution Approach 2:
The continuous motion imaging technique serves multiple functions simultaneously: it captures the entire contrast bolus passage, covers the extended field of view, provides time-resolved vascular information, and eliminates the need for multiple separate imaging sequences and post-processing registration steps
3Loss of time
If the center of k-space is sampled at a higher temporal rate than peripheral k-space, then time resolution for contrast bolus tracking is improved, but data acquisition complexity increases
Solution Approach 1:
Different regions of k-space are sampled at different temporal rates according to their specific requirements. The center of k-space, which contains the contrast bolus information, is sampled at a higher temporal rate to capture rapid changes in contrast concentration. Peripheral k-space regions are sampled at lower rates since they represent less time-critical anatomical details, optimizing temporal resolution where needed while reducing overall data acquisition complexity
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 acquisition of time-resolved three-dimensional images that can study the timing of contrast inflow into peripheral vessels, reducing the need for multiple repositionings and contrast injections, thereby improving diagnostic efficiency and reducing costs.
Implementation Method 1
Magnetic resonance angiography (MRA) uses the nuclear magnetic resonance (NMR) phenomenon to produce images of the human vasculature
Implementation Method 2
When utilizing these signals to produce images, magnetic field gradients (Gx Gy and Gz) are employed
Data Source
AI summary
MRA data is acquired from an extended field of view by translating the patient through the bore of the MRI system as three-dimensional MRA data sets are acquired and time-resolved images reconstructed. The leading edge of a contrast bolus can be tracked in these images and parameters such as bolus velocity and bolus arrival time can be calculated to provide functional information in addition to anatomical information. Temporal resolution is improved by undersampling peripheral k-space and sampling the center of k-space at a higher temporal rate.