SVE Reconstruction for Phase Contrast MRI Temporal Resolution
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Solution Overview
Problem
Conventional phase-contrast magnetic resonance imaging (PC-MRI) techniques require twice as much data as standard MRI scans, leading to a degradation in temporal sampling rate and doubling of acquisition time due to the need for additional datasets to account for background phase variations, which limits the temporal resolution and makes real-time flow quantification impractical.
Innovation Solution
The Shared Velocity Encoding (SVE) reconstruction method reuses adjacent k-space data to reconstruct twice as many frames, allowing for improved temporal resolution by sharing data between consecutive images with alternate polarity velocity encoding, thereby reducing the need for additional reference data and minimizing sensitivity to respiratory and cardiac motions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PC-MRI techniques are used to account for background phase variations, then measurement precision is improved, but acquisition time is doubled and temporal resolution is degraded
Solution Approach 1:
The patent segments the k-space data into different regions (central k-space and peripheral k-space) and applies different processing strategies to each. The central k-space data is used for velocity encoding while the peripheral k-space data is used for background phase correction, allowing simultaneous acquisition of both types of information without requiring separate datasets
Solution Approach 2:
The patent makes the k-space data serve multiple functions: the same acquired data is used both for velocity encoding and for background phase correction. By using the peripheral k-space data from the velocity-encoded image to correct the central k-space data, the system eliminates the need for separate reference images while maintaining measurement accuracy
2Measurement precision
If twice as much data is acquired for PC-MRI, then measurement precision is improved, but productivity is reduced due to doubled acquisition time
Solution Approach 1:
The patent recovers useful information from the peripheral k-space data that would otherwise be discarded or underutilized. Instead of treating all k-space data equally, the method selectively uses peripheral data for background phase correction, thereby recovering the temporal resolution that would be lost with conventional methods
Solution Approach 2:
The patent introduces a dimensional approach by separating k-space data into central and peripheral regions, treating them differently in the reconstruction process. This dimensional differentiation allows the system to maintain high temporal resolution while achieving accurate velocity measurement without requiring twice the data
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
SVE reconstruction increases effective temporal resolution by a factor of two, enabling high temporal resolution real-time velocity mapping and reducing the temporal resolution penalty associated with additional reference data acquisition, while maintaining accuracy in blood flow velocity measurement.
Implementation Method 1
The velocity is encoded by applying appropriately designed gradient lobes in the velocity encoding direction; bipolar gradient lobes are one example. The two lobes of the bipolar gradient are created so their areas are equal and opposite. This makes the zeroth moment, m0, of the gradient waveform equal to 0 after the bipolar lobes. Since m0=0, no phase is imparted to static spins. Spins moving along the bipolar gradient direction experience a phase shift due to the difference in their positions from the first and second lobes of the bipolar gradient. This phase shift is proportional by the gyromagnetic ratio to the first moment, m1, of the bipolar gradient.
Implementation Method 2
This phase shift is proportional by the gyromagnetic ratio to the first moment, m1, of the bipolar gradient. φv=v*γ*m1
Data Source
AI summary
An exemplary embodiment of the present invention includes a method for increasing temporal resolution in Phase Contrast (PC) MR imaging. The increased temporal resolution may be obtained by reusing information encoded into phase of an MRI signal where said reuse occurs prior to the difference reconstruction.