Multi-Nuclide MRI SAR Calculation for RF Hotspot Optimization
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Solution Overview
Problem
Current methods for determining local specific absorption rate (SAR) in magnetic resonance imaging fail to account for the spatial correlation between different nuclides, leading to conservative estimates and limiting the performance and design scope of radio frequency pulses.
Innovation Solution
An ascertainment algorithm that jointly considers nuclides and their assigned logical coil channels to ascertain local specific absorption rate information, using a computing matrix that incorporates location information for all nuclides, allowing for hotspot evaluation and optimization of radio frequency pulse design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If independent SAR calculation for each nuclide is performed, then patient safety is ensured through conservative estimates, but image recording performance is limited and design scope is restricted
Solution Approach 1:
The patent combines the SAR calculations for multiple nuclides into a unified joint calculation framework. Instead of independently calculating SAR for each nuclide and summing the results, the invention integrates the calculations to account for spatial correlations between hotspots of different nuclides, thereby improving image recording performance while maintaining patient safety.
Solution Approach 2:
The patent introduces a computing matrix as an intermediary tool that stores pre-calculated SAR values for different subvolumes and nuclides. This matrix serves as a mediator between the complex multi-nuclide parallel transmission system and the final SAR assessment, enabling efficient joint calculation by looking up and combining pre-computed values according to actual actuation variables.
2Reliability
If conservative SAR estimation is used by summing independent nuclide SAR values, then patient safety is guaranteed, but computational complexity increases and performance optimization is hindered
Solution Approach 1:
The patent performs preliminary SAR calculations for each nuclide and stores the results in a computing matrix before actual imaging. By pre-calculating and storing SAR values for different subvolumes and nuclides, the system avoids repeated complex calculations during imaging, reducing computational complexity while maintaining accurate SAR assessment.
Solution Approach 2:
The patent creates a computational model (computing matrix) that copies and stores SAR characteristics for different nuclides and subvolumes. This virtual representation allows the system to efficiently assess SAR by combining pre-stored values according to actual actuation variables, rather than performing full electromagnetic simulations each time.
3Adaptability or versatility
If parallel transmission techniques are used for multiple nuclides, then additional degrees of freedom are available for hotspot prevention, but complex heating patterns result that are difficult to manage
Solution Approach 1:
The patent applies local quality by dividing the imaging volume into multiple subvolumes and calculating SAR independently for each subvolume. This allows the system to manage complex heating patterns locally in each subvolume while maintaining global SAR control, making the complex multi-nuclide parallel transmission heating patterns more manageable.
Solution Approach 2:
The patent segments the imaging volume into multiple subvolumes and processes SAR calculation for each subvolume separately. This segmentation approach breaks down the complex multi-nuclide heating pattern management into smaller, more manageable units, allowing independent optimization for each subvolume while maintaining overall SAR compliance.
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 optimal utilization of performance scope by adjusting hotspots across different nuclides, ensuring adherence to SAR limits and improving image recording quality while reducing computational complexity.
Implementation Method 1
radio frequency pulses which are configured to manipulate the nuclear spins of at least two different nuclides
Implementation Method 2
an input of energy due to radio frequency pulses used during magnetic resonance sequences. This energy input, in particular as heat, into the patient as the object is described by the specific absorption rate (SAR)
Data Source
AI summary
A method is provided for ascertaining an item of local specific absorption rate (SAR) information in an object under effect of specified radio frequency pulses of a candidate group output with a radio frequency coil arrangement of a magnetic resonance facility, wherein the radio frequency pulses are embodied for manipulating nuclear spins of at least two different nuclides. The method includes implementing a parallel transmission technique for at least one nuclide; generating actuation variables assigned in accordance with the candidate group due to the actuation of the radio frequency coil arrangement; and ascertaining the item of local SAR information by an ascertainment algorithm using the actuation variables as the input data. The ascertainment algorithm is parameterized by taking into account the nuclides and respectively assigned logical coil channels thereof such that the item of local SAR information is jointly ascertained for all nuclides with the same local location reference.