Independent Phase Modulation for Dual-Volume MRI
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Solution Overview
Problem
Current MRI techniques require encoding across both volumes of interest and the space between them, leading to inefficiencies and increased scan times, especially in applications like bilateral breast imaging, where simultaneous imaging of multiple volumes is necessary.
Innovation Solution
Independent phase modulation of each slab allows for the elimination of the need to encode empty space between slabs by shifting their positions in k-space, enabling simultaneous imaging of multiple volumes without encoding the space between, thereby reducing the required imaging field of view and improving signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If encoding is performed across both volumes of interest and the space between them, then complete volumetric coverage is achieved, but scan time increases and imaging efficiency decreases
Solution Approach 1:
The imaging volume is segmented into multiple distinct slabs, each excited independently with its own phase modulation. This allows separate encoding of each slab without requiring encoding of the space between them, thereby reducing scan time while maintaining complete coverage of the volumes of interest
Solution Approach 2:
Phase modulation is applied in the frequency-encoding dimension to shift and separate the signal from different slabs in k-space. This dimensional approach allows multiple slabs to be encoded independently along the frequency-encode direction, eliminating the need to encode the space between slabs in the phase-encode direction
2Productivity
If multiple volumes are imaged simultaneously with standard encoding, then imaging efficiency improves, but artifact generation increases
Solution Approach 1:
Each volume is segmented into distinct slabs with independent phase modulation applied. This segmentation allows the signal from each slab to be separately encoded and reconstructed, preventing the mixing of signals that causes pulsatility artifacts while maintaining simultaneous imaging capability
Solution Approach 2:
Different phase modulation parameters are applied to different slabs based on their specific positions and characteristics. This local customization of encoding parameters optimizes the signal separation for each individual slab, reducing artifacts while maintaining high imaging efficiency
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 results in a more time-efficient and artifact-reduced imaging process, achieving a 20% reduction in scan time and minimizing pulsatility artifacts, while being compatible with various pulse sequences and parallel imaging methods.
Implementation Method 1
nuclear magnetic moments are excited at specific spin precession frequencies which are proportional to the local magnetic field. The radio-frequency signals resulting from the precession of these spins are received using pickup coils
Implementation Method 2
The first volume is excited with a first linearly varying phase with respect to k-space. The second volume is excited with a second linearly varying phase with respect to k-space, wherein the first linearly varying phase has a different slope than the second linearly varying phase
Data Source
AI summary
A method for magnetic resonance imaging (MRI) a first volume and a second volume spaced apart from the first volume is provided. The first volume is excited with a first linearly varying phase with respect to k-space. The second volume is excited with a second linearly varying phase with respect to k-space, wherein the first linearly varying phase has a different slope than the second linearly varying phase. Data in k-space is acquired line by line. The acquired data in k-space is Fourier transformed to image space. An image is formed with a first volume image and a second volume image from the transformed data. Use of phase modulation allows imaging with a reduced field-of-view, which can result in faster scan times or improved performance of parallel imaging acquisition strategies.