2D Sub-Volume MRI Acquisition Reducing Spin Saturation
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Solution Overview
Problem
Magnetic resonance imaging (MRI) techniques face limitations in efficiently acquiring large target volumes with flexible adaptation of acquisition parameters and reducing movement artifacts, particularly in multi-slice acquisitions where contrast and saturation issues arise.
Innovation Solution
The method involves dividing the target volume into sub-volumes in a two-dimensional plane using two orthogonal radio-frequency pulses for targeted excitation and data acquisition, allowing for improved flexibility and reduced saturation by optimizing shim settings and acquisition order, such as sequential or diagonal acquisition of sub-volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multi-slice acquisition is used to cover large target volume, then coverage area is improved, but saturation of spin system increases and contrast deteriorates
Solution Approach 1:
The target volume is divided into multiple sub-volumes defined by a two-dimensional matrix of slice pairs, where each sub-volume is acquired separately with its own excitation and refocusing pulses. This segmentation allows independent control of acquisition parameters for each sub-volume, preventing spin system saturation while maintaining comprehensive coverage.
Solution Approach 2:
The invention extends the traditional one-dimensional slice selection to two-dimensional slice pairs by introducing a matrix structure with rows and columns. Two radio-frequency pulses act in orthogonal directions within the plane perpendicular to the readout direction, creating a two-dimensional grid of sub-volumes that enables more flexible and efficient coverage.
2Productivity
If conventional multi-slice acquisition is used, then acquisition speed is limited, but flexibility in adapting acquisition parameters for different regions is reduced
Solution Approach 1:
By segmenting the target volume into multiple independently controllable sub-volumes arranged in a two-dimensional matrix, each sub-volume can be acquired with optimized parameters tailored to its specific characteristics. This enables both faster parallel acquisition and region-specific parameter adaptation simultaneously.
Solution Approach 2:
The acquisition method dynamically adapts parameters such as shim settings, echo train length, and excitation pulse characteristics for each individual sub-volume based on its location and tissue characteristics. This dynamic parameter adjustment optimizes both acquisition efficiency and image quality for each region.
3Manufacturing precision
If two radio-frequency pulses are used for sub-volume selection, then sub-volume definition precision is improved, but device complexity increases
Solution Approach 1:
The two radio-frequency pulses serve multiple functions: they define the two-dimensional slice pair geometry, select specific sub-volumes through their orthogonal orientations, and enable parallel acquisition of multiple sub-volumes. This multi-functionality achieves precise sub-volume definition without proportionally increasing system complexity.
Solution Approach 2:
The invention utilizes parameter changes in the radio-frequency pulses, specifically varying their orientation angles in the plane perpendicular to the readout direction. By systematically varying these angular parameters across the matrix, precise sub-volume selection is achieved while maintaining a relatively simple pulse sequence structure based on standard spin echo or gradient echo techniques.
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 enhances the flexibility and speed of MRI data acquisition, reduces movement artifacts, and allows for more precise shim settings, leading to improved image quality and shorter acquisition times compared to conventional multi-slice methods.
Implementation Method 1
using two radio-frequency pulses of a spin echo-based sequence one can select not only slices in one dimension but also parallelograms in two dimensions
Implementation Method 2
acquire a magnetic resonance image data set of a target volume with a magnetic resonance device
Data Source
AI summary
In a method to acquire a magnetic resonance image data set of a target volume with a magnetic resonance device, wherein the target volume is composed of a number of sub-volumes defined in a two-dimensional plane orthogonal to the readout direction, for each sub-volume, in order to acquire a partial data set of a sub-volume, a targeted excitation of the sub-volume and a data acquisition from that sub-volume to measure the partial data set take place by radiation of a first radio-frequency pulse acting in a first direction of the plane and radiation of a second radio-frequency pulse acting in a second direction that is orthogonal to the first direction. The partial data sets are combined into the magnetic resonance data set.