VIPR MRI Inversion Recovery for Temporal Resolution
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Solution Overview
Problem
Conventional MRI techniques face a trade-off between spatial and temporal resolution due to the need for fully sampling k-space, which limits the acquisition rate of image frames and often results in lower image quality when undersampling is used to improve temporal resolution.
Innovation Solution
The method employs a system and method for inversion-recovery imaging using radial projections, allowing for flexible selection of the number of consecutive projections to combine and adjust the repetition times (TRs), enabling retrospective combination of data to achieve improved image quality and subject-specific contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fully-sampled MRI is used, then spatial resolution is maintained, but temporal resolution deteriorates due to long acquisition time
Solution Approach 1:
The patent applies partial sampling of k-space by acquiring only a subset of radial projections rather than fully sampling all required views. This undersampling approach reduces acquisition time while maintaining acceptable image quality through selective sampling of the most informative k-space regions and advanced reconstruction techniques that compensate for the missing data.
Solution Approach 2:
The patent segments the k-space sampling into multiple radial projections acquired at different time points. By dividing the complete k-space sampling into sequential angular segments and using view-ordering techniques, the system enables parallel acquisition of multiple projections, thereby reducing total acquisition time while preserving spatial resolution through proper reconstruction of the segmented data.
2Productivity
If undersampling is used to improve temporal resolution, then acquisition time is reduced, but image quality deteriorates
Solution Approach 1:
The patent changes the sampling parameters by using non-Cartesian radial trajectories instead of conventional Cartesian grids. This parameter change allows for more efficient sampling of k-space, concentrating samples where they provide maximum information content. Combined with advanced reconstruction algorithms, this enables high temporal resolution while maintaining image quality by optimally distributing the reduced number of samples.
Solution Approach 2:
The patent introduces advanced reconstruction algorithms as an intermediary between the undersampled raw data and the final image. These reconstruction techniques (such as iterative reconstruction, compressed sensing, or parallel imaging methods) act as mediators that recover missing information from the undersampled data, thereby preserving image quality despite the reduced sampling density.
3Manufacturing precision
If more radial projections are acquired to improve image quality, then spatial resolution is improved, but temporal resolution deteriorates
Solution Approach 1:
The patent employs periodic acquisition of radial projections at regular angular intervals during a single TR period. This periodic sampling pattern allows multiple projections to be acquired within the available time window, improving image quality through increased sampling density while maintaining temporal resolution by utilizing the periodic nature of the radial acquisition within each repetition cycle.
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 allows for the acquisition of multiple images with different contrasts in the same time as a single contrast setting, reducing motion artifacts and improving image quality, especially in pediatric and tumor imaging, while enabling accurate T1 quantification and finer temporal resolution.
Implementation Method 1
an inversion recovery ('IR') radio frequency ('RF') pulse is applied to a subject such that net longitudinal magnetization in the subject is substantially inverted and begins to relax back to equilibrium
Implementation Method 2
net longitudinal magnetization in the subject is substantially inverted and begins to relax back to equilibrium
Implementation Method 3
A NMR signal is emitted by the excited spins after the excitation signal B1 is terminated, this signal may be received and processed to form an image
Implementation Method 4
gradients vary according to the particular localization method being used... employing magnetic fields (Gx, Gy, and Gz) that have the same direction as the polarizing field B0, but which have a gradient along the respective x, y, and z axes
Data Source
AI summary
Described here are a system and method for obtaining a time series of images that depict a subject using an inversion recovery (“IR”) pulse sequence with a unique data acquisition scheme that allows for the retrospective identification of an image having an optimal tissue contrast. Data acquisition is performed using a radial acquisition scheme such as, preferably, a vastly undersampled isotropic projection reconstruction (“VIPR”) scheme. Using VIPR and IR, combined with a unique projection ordering, a series of three-dimensional, high spatial resolution images with multiple different image contrasts can be obtained.