Non-Unique Gradient Fields for Dental MRI Resolution
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Solution Overview
Problem
Conventional MRI systems for dental imaging face challenges in achieving high spatial resolution and short echo times due to limitations in gradient field steepness and power requirements, making it difficult to effectively image small dental structures without excessive biological stimulation or high costs.
Innovation Solution
A gradient system generating three superimposed gradient fields, at least one of which is non-unique and has areas of equal strength extending parallel or orthogonally to the U-shaped center plane of the teeth, allowing for steeper and faster gradient switching without biological limitations, suitable for UTE sequences and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional MRI gradient systems are used with large field of view, then the system can cover the entire imaging region, but the gradient amplitudes become excessively high causing biological stimulation effects or requiring extremely expensive gradient systems
Solution Approach 1:
The patent divides the imaging space into multiple regions with different gradient characteristics. Steep gradients are applied only in the dental region of interest where high resolution is needed, while shallower gradients are used in surrounding areas. This segmentation allows achieving high spatial resolution for teeth imaging without subjecting the entire field of view to excessively high gradient amplitudes that cause biological stimulation.
2Area of stationary object
If conventional MRI gradient systems are used with large field of view, then the system can cover the entire imaging region, but the gradient system becomes extremely expensive and economically unviable
Solution Approach 1:
The patent implements local quality by applying steep gradient fields only in the specific dental region where high spatial resolution is required, rather than across the entire large field of view. This localized approach to gradient application reduces the overall system requirements and associated costs, making the system economically viable while still achieving the necessary imaging quality for dental structures.
3Loss of time
If steep gradient fields are used to achieve short echo times for bound proton imaging, then the phase difference develops quickly enough, but the gradient amplitudes become biologically impossible or require extremely expensive systems
Solution Approach 1:
The patent employs dynamic gradient switching where the gradient amplitude is rapidly changed over time. Very steep gradients are applied only during the brief period needed to encode the dental region, then quickly reduced or switched off. This dynamic approach allows achieving the necessary phase encoding for short echo times without maintaining high gradient amplitudes that would cause biological stimulation effects.
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
Enables high-resolution, cost-effective, and efficient MR imaging of teeth with low power requirements, facilitating the generation of high-quality images and reducing the need for expensive gradient systems.
Implementation Method 1
A gradient system is used which generates three superimposed gradient fields
Implementation Method 2
the nuclear spins of the object orient along the basic magnetic field. To trigger nuclear spin resonances, high-frequency excitation pulses (HF pulses) are irradiated into the object under examination, the triggered nuclear spin resonances are measured as so-called k-space data
Data Source
AI summary
A gradient system according to the invention generates three superimposed gradient fields of which at least one of the three gradient fields is not unique in space (i.e. not bijective) and at least one of the three gradient has areas of the same field strength, which extend in parallel or orthogonally to a approximately U-shaped center plane of the teeth of one jaw of a patient.