Spatiotemporal Phase Correction for MRI Velocity Accuracy
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Solution Overview
Problem
Phase contrast Magnetic Resonance Imaging (PC-MRI) techniques face challenges in accurately measuring fluid or tissue velocities due to background phase offsets caused by eddy currents and concomitant gradient terms, which existing correction methods fail to adequately address, especially in anatomical-specific and time-stable corrections.
Innovation Solution
A spatiotemporal background phase correction method is introduced, utilizing filters based on physiological limits such as vessel diameter and respiratory frequency to correct phase contrast velocity encoded MRI images by applying a spatiotemporal filter to the complex image, allowing for low-pass filtering and complex division to yield a corrected image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate phantom scan or physical field measurement is performed to compensate for eddy currents, then background phase error compensation is improved, but scan time increases and anatomical specificity is lost
Solution Approach 1:
The patent extracts and removes the background phase error component from the total phase signal by identifying stationary tissue regions and calculating their phase characteristics, then subtracts this background phase from the velocity-encoded images to isolate the true flow signal
Solution Approach 2:
The patent uses the patient's own stationary tissue within the scan region to generate the background phase reference, eliminating the need for separate phantom scans or field measurements while maintaining anatomical specificity
2Measurement precision
If separate phantom scan or physical field measurement is performed to compensate for eddy currents, then background phase error compensation is improved, but anatomical specificity is reduced
Solution Approach 1:
The patent applies background phase correction locally to each patient's anatomy by identifying and using stationary tissue regions within the specific scan area, making the correction anatomically specific rather than using a generic phantom-based approach
3Measurement precision
If high order polynomial fitting is used for post-processing phase correction, then phase correction accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent introduces an intermediary approach by using stationary tissue phase as a physical reference that naturally represents the background phase, avoiding the need for complex polynomial fitting algorithms while maintaining correction accuracy
4Measurement precision
If eddy current induced phase offsets are measured separately, then phase error characterization is improved, but temporal stability is compromised
Solution Approach 1:
The patent continuously measures the background phase throughout the scan using stationary tissue in each velocity-encoded image, ensuring temporal stability and capturing any drift in eddy current effects without requiring separate measurements
Data Source
AI summary
A computer-implemented method for performing spatiotemporal background phase correction for phase contrast velocity encoded magnetic resonance imaging includes performing a phase contrast magnetic resonance imaging scan of a region of interest within a patient to yield a complex image and calculating a plurality of filter cut-off frequencies based on physiological limits associated with the patient. A spatiotemporal filter is created based on the plurality of filter cut-off frequencies. This spatiotemporal filter is applied to the complex image to yield a low-pass filtered complex image. Then, complex division is performed using the complex image and the low-pass filtered complex image to yield a corrected image.