Diffusion Tensor MRI via Cylindrical Symmetry
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Solution Overview
Problem
Current methods for determining diffusion tensors in magnetic resonance tomography require numerous measurements, leading to extended measuring times and poor signal-to-noise ratios due to the need for multiple diffusion-encoded images in different directions.
Innovation Solution
The method utilizes symmetry properties of the examination object to reduce the number of measurements by acquiring images in fewer directions, leveraging symmetry operations to map measured values from one volume element to another, thereby determining diffusion tensors with improved signal-noise ratios and reduced measuring time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple diffusion-encoded images in different directions are acquired to determine all components of the diffusion tensor, then measurement completeness is improved, but measuring time is extended and signal-to-noise ratio deteriorates
Solution Approach 1:
The patent exploits the inherent rotational symmetry of cylindrical structures (such as blood vessels or nerve fibers) to reduce the number of required diffusion tensor measurements. Instead of acquiring 6 measurements in different directions as required by conventional methods, the invention acquires only 3 measurements at specific angles (e.g., 0°, 60°, 120°) relative to the cylindrical structure's axis. The symmetry of the cylindrical geometry allows the diffusion tensor components to be determined from these fewer measurements, as the rotational symmetry provides additional constraints that reduce the independent measurements needed.
2Measurement precision
If multiple diffusion-encoded images in different directions are acquired to determine all components of the diffusion tensor, then measurement completeness is improved, but signal-to-noise ratio deteriorates
Solution Approach 1:
By reducing the number of measurements from 6 to 3 based on cylindrical symmetry, the invention inherently improves the signal-to-noise ratio. Each individual measurement contributes more significantly to the final tensor determination when fewer total measurements are made, as the same total measurement time is concentrated into fewer, higher-quality acquisitions rather than being distributed across multiple lower-signal measurements.
3Measurement precision
If conventional diffusion tensor measurement methods are used, then all tensor components can be determined, but the number of measurements required is large
Solution Approach 1:
The invention reduces the measurement count from 6 to 3 by exploiting cylindrical symmetry, effectively doubling the measurement efficiency for this specific geometric class. The symmetry-based approach maintains complete diffusion tensor determination while halving the number of required acquisitions, thereby significantly improving productivity for examinations involving cylindrical structures.
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 allows for the complete determination of diffusion tensors using fewer images, typically three diffusion-encoded and one reference measurement, significantly reducing measuring time while enhancing the signal-noise ratio and image quality.
Implementation Method 1
align nuclear spins of the examination object with a strong outer magnetic field
Implementation Method 2
execute the same for precession about this alignment
Implementation Method 3
The precession or return of the spins from this excited state into a state with less energy in turn generates, as a response, a magnetic alternating field
Implementation Method 4
With the aid of magnetic gradient fields, a spatial encoding is imprinted on the signals
Implementation Method 5
Diffusion of substances in the examination object, (e.g., water or hydrogen-containing substances), is described by a diffusion tensor
Data Source
AI summary
A magnetic resonance tomography scanner is provided for the determination a diffusion tensor of an examination object, and a method is provided for operating the magnetic resonance tomography scanner. The magnetic resonance tomography scanner acquires a volume image of the examination object by imaging magnetic resonance tomography without diffusion encoding. The control system segments the image according to diffusion-relevant symmetry properties and also determines volume elements of a symmetry group. A first and a second component of a diffusion tensor are acquired by the magnetic resonance tomography scanner at different angles and the control unit uses the symmetry property with the acquired components and the volume image to determine a diffusion tensor for the volume elements.