Segmented RF Pulse Virtual Receivers for MRI Scan Acceleration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic resonance imaging (MRI) techniques face challenges with long scan times due to the need for full sampling of multidimensional RF pulses, which are sensitive to magnetic field inhomogeneity and result in low bandwidth, limiting their utility in applications like localized spectroscopy and inner volume imaging.
Innovation Solution
The method involves segmenting RF pulses into shorter segments, allowing for undersampling during data acquisition and treating each segment as a virtual receiver for parallel image reconstruction, thereby reducing scan time without compromising image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multidimensional RF pulses are used for localized spectroscopy and inner volume imaging, then robustness to B0 inhomogeneity is improved, but bandwidth decreases due to extended pulse length
Solution Approach 1:
The multidimensional RF pulse is divided into multiple one-dimensional pulse segments that are applied sequentially along different k-space trajectories. Each segment has a shorter duration and higher bandwidth while collectively providing the full multidimensional excitation profile, thus resolving the contradiction between robustness and bandwidth.
2Speed
If multidimensional RF pulses are segmented and fully sampled per excitation segment, then excitation bandwidth is increased, but scan time increases linearly with the number of pulse segments
Solution Approach 1:
Instead of fully sampling k-space with each pulse segment, the method uses partial sampling (undersampling) where each segment acquires only a portion of the required k-space data. The missing data is reconstructed using parallel imaging techniques, thereby reducing scan time while maintaining image quality.
3Speed
If undersampling of excitation k-space is used to achieve shorter pulse length and increased bandwidth, then pulse bandwidth is improved, but image quality deteriorates due to insufficient sampling
Solution Approach 1:
The method introduces virtual receiver coils created from the segmented pulse data as an intermediary mechanism. These virtual coils provide spatial encoding information that enables parallel imaging reconstruction, allowing undersampled data to be combined into a complete image without loss of quality, thus mediating between bandwidth and image quality.
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 accelerates MRI data acquisition, improves robustness to magnetic field inhomogeneity, and enhances imaging techniques such as inner volume spectroscopy and B1-gradient based imaging, while maintaining image quality by using segmented RF pulses as virtual receivers for parallel reconstruction.
Implementation Method 1
magnetic resonance imaging (MRI) system. The method includes selecting with a computer system, a radio frequency (RF) pulse. The RF pulse is then segmented in order to generate a series of RF pulse segments. Data are acquired from a subject using an MRI system implementing a pulse sequence that includes the series of RF pulse segments.
Data Source
AI summary
Accelerated data acquisition using two-dimensional (“2D”) radio frequency (“RF”) pulse segments as virtual receivers for a parallel image reconstruction technique, such as GRAPPA, is provided. Data acquisition is accelerated using segmented RF pulses for excitation, refocusing, or both, and undersampling k-space along a dimension of the RF pulse segments. In this way, parallel image reconstruction techniques, such as GRAPPA, can be adapted to work with a single RF receive coil. By undersampling the data acquisition and finding correlations between the data from different segments, unsampled data can be recovered. This shortens scan times, yielding the advantages of segmented pulses without the formerly required long scans.