3D MRI Scan Sequence Using 2D CAIPIRINHA Undersampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Standard 2D SENSE and 2D GRAPPA undersampling methods for 3D MRI scanning result in artifacts due to insufficient sensitivity variation and reliance on coil distribution, particularly in 3D fast spin echo sequences, leading to suboptimal image quality and longer scan times.
Innovation Solution
Implementing the 2D CAIPIRINHA undersampling method, which reorganizes k-space data into multiple basic parallel reconstruction units with a staggered sampling strategy, allowing for controlled aliasing and increased coil sensitivity, thereby improving image quality and reducing scan time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard 2D SENSE or 2D GRAPPA undersampling methods are used for 3D MRI scanning, then image reconstruction can be performed with coil sensitivity variation, but artifacts appear in the reconstructed image due to insufficient sensitivity variation and reliance on coil distribution
Solution Approach 1:
The patent transitions from 2D parallel imaging (SENSE/GRAPPA) to 3D parallel imaging by introducing a third encoding dimension. The 3D SENSE method acquires and reconstructs data in three dimensions (x, y, z), utilizing coil sensitivity variation across all three dimensions to eliminate artifacts that plague 2D methods. This dimensional expansion provides sufficient sensitivity variation for artifact-free reconstruction.
2Productivity
If 2D SENSE or 2D GRAPPA undersampling methods are employed, then reconstruction can be achieved with rectangular undersampling model, but scan time is increased due to serious reliance on coil distribution
Solution Approach 1:
The patent implements 3D parallel imaging that exploits sensitivity variation in three spatial dimensions, enabling higher acceleration factors compared to 2D methods. By utilizing the additional z-dimension for encoding and reconstruction, the system can achieve greater speedup without compromising image quality or relying excessively on coil geometry.
Solution Approach 2:
The patent changes the fundamental parameters of the imaging system by moving from 2D to 3D encoding schemes. This involves modifying the k-space sampling patterns, gradient encoding sequences, and reconstruction algorithms to operate in three dimensions, thereby achieving improved scan efficiency and reduced acquisition time.
3Measurement precision
If conventional 3D MRI scanning is performed without optimized undersampling, then complete k-space data can be acquired, but scan time is prolonged and patient comfort is reduced
Solution Approach 1:
The patent applies undersampling techniques in 3D parallel imaging, acquiring only a subset of k-space data points that are sufficient for high-quality reconstruction when combined with coil sensitivity information. This partial sampling approach significantly reduces scan time while maintaining measurement precision through the power of parallel imaging reconstruction.
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
The 2D CAIPIRINHA undersampling method reduces artifacts, enhances image quality, and shortens scan time by stabilizing reconstruction conditions and increasing coil sensitivity, while maintaining a high signal-to-noise ratio, thus improving the comfort and outcome of MRI examinations.
Implementation Method 1
A radio frequency (RF) pulse of a specific frequency is used to excite the atomic nuclei in the external magnetic field such that their spin axes deviate from the positive longitudinal axis or negative longitudinal axis, and resonance occurs—this is the phenomenon of magnetic resonance.
Implementation Method 2
Once emission of the RF pulse has ended, the excited atomic nuclei emit an echo signal, gradually releasing the absorbed energy in the form of electromagnetic waves
Data Source
AI summary
In an MRI method and apparatus a 3D magnetic resonance scan sequence is performed to acquire MR raw data, which are entered into k-space with 2D CAIPIRINHA undersampling. The sampled data are reorganized into data blocks that each contain one sampled k-space location. The data blocks are extracted from k-space in a predetermined sequence, and image data are reconstructed from the k-space data respectively in the extracted data blocks. The application of the 2D CAIPIRINHA undersampling method with corresponding reorganized data blocks into a 3D scan sequence, in particular a SPACE scan sequence, significantly improves the comfort of an examination subject as well as the overall image quality thereof.