MR Image Reconstruction Using Antenna Sensitivity Profiles
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Solution Overview
Problem
Conventional MR imaging methods struggle to acquire and reconstruct images of tissues with short T1 and T2 relaxation times due to dead time limitations in magnetic resonance scanners, leading to incomplete data acquisition in k-space, especially at the center, resulting in image artifacts and reduced quality.
Innovation Solution
The method involves using multiple receiving antennas with smaller apertures to acquire data at specific k-space points, allowing the main lobe of the antenna's spectral sensitivity to extend over adjacent points, enabling the calculation of missing data and reconstruction of image points even with incomplete sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MR scanning is used with standard dead time, then reliable receiving coil operation is maintained, but data acquisition in the k-space center region is lost leading to severe image artifacts
Solution Approach 1:
The patent segments the data acquisition process into two distinct phases: a first data acquisition during the dead time period that captures partial k-space information, and a second data acquisition after dead time that captures the remaining k-space information. This segmentation allows the system to utilize data from both periods, preventing complete loss of k-space center information while maintaining receiving coil reliability.
Solution Approach 2:
The patent performs preliminary action by acquiring data during the dead time period before the receiving coils are fully operational. This preliminary data acquisition captures valuable k-space information that would otherwise be lost, and this data is then combined with subsequent data acquisition to reconstruct complete images without artifacts.
2Productivity
If radial trajectory data acquisition is used, then data acquisition speed is improved, but the k-space center region remains undersampled leading to incorrect image contrast
Solution Approach 1:
The patent merges two different data acquisition approaches: radial trajectory acquisition (which provides fast sampling of outer k-space regions) and Cartesian grid acquisition (which provides complete sampling of the k-space center). By combining data from both trajectories and using appropriate reconstruction algorithms, the system achieves both fast acquisition speed and accurate image contrast.
Solution Approach 2:
The patent applies local quality by using different sampling strategies for different regions of k-space: radial trajectories are used for the outer regions where fast sampling is beneficial, while the k-space center region is specifically targeted with additional sampling points to ensure adequate density for correct image contrast. Each region of k-space receives the appropriate sampling density for its specific requirements.
3Loss of information
If multiple receiving antennas with smaller apertures are used, then incomplete k-space sampling can be compensated, but device complexity increases
Solution Approach 1:
The patent introduces sensitivity profiles as an intermediary mathematical tool that characterizes the spatial sensitivity characteristics of each receiving antenna. These sensitivity profiles serve as mediators that allow the reconstruction algorithm to correctly combine data from multiple antennas with different apertures and positions, compensating for incomplete k-space sampling while managing device complexity through software-based processing rather than requiring uniformly complex hardware configurations.
Data Source
AI summary
A magnetic resonance (MR) image is created by executing an imaging sequence with an MR apparatus, wherein data in k-space are acquired using multiple receiving antennae, and reconstruction of all image points that correspond to all k-space points belonging to the imaging sequence takes place using a sensitivity profile of the receiving antennae in order to also take account of data at k-space points at positions at which no data were acquired. Data acquired at a number of positions of particular k-space points, the number of the particular k-space points being smaller than the number of all k-space points belonging to the imaging sequence. The aperture of each of the receiving antennae is configured such that, for acquisition of data at a respective k-space point, the spectral main lobe of the respective receiving antenna also extends over k-space points adjacent to the respective k-space point.