Rapid PNS Threshold Prediction for MRI Gradient Coil Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for assessing peripheral nerve stimulation (PNS) of gradient coils, such as those used in MRI, are time-consuming and not suitable for repeated evaluations during numerical optimization, due to the complexity of neurodynamic models and the need for extensive simulations.
Innovation Solution
A rapid linear PNS predictor, or 'oracle,' is developed to estimate PNS thresholds using a coil specific PNS P-matrix generated from a PNS Huygens' P-matrix defined on a Huygens' surface of a body model, allowing for quick assessment and optimization of coil designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full neurodynamic model simulations are used for PNS assessment, then measurement precision is improved, but productivity deteriorates due to computation time taking multiple hours to several days
Solution Approach 1:
The patent creates a simplified linear PNS predictor model that copies the essential functionality of the full neurodynamic model but uses linear operations instead of complex nonlinear simulations. This surrogate model reproduces PNS threshold predictions with sufficient accuracy for optimization purposes while reducing computation time from hours/days to milliseconds.
Solution Approach 2:
The patent precomputes a P-matrix that contains pre-calculated influence coefficients for each coil element and nerve segment combination. This preliminary computation allows rapid PNS assessment during optimization by simply multiplying the P-matrix with coil currents, eliminating the need for repeated full neurodynamic simulations.
2Measurement precision
If full neurodynamic model simulations are used for PNS assessment, then measurement precision is improved, but device complexity worsens due to the need for complex electromagnetic and neurodynamic modeling frameworks
Solution Approach 1:
The patent extracts only the essential linear components needed for PNS threshold prediction from the full neurodynamic model. By taking out the critical electric field-to-PNS threshold relationship and representing it through a linear P-matrix, the complex nonlinear neurodynamic simulations are eliminated while retaining sufficient prediction accuracy for coil optimization.
Solution Approach 2:
The patent substitutes the complex biological neurodynamic system with a simplified linear mathematical model. The nonlinear ion channel dynamics and action potential generation processes are replaced with a linear P-matrix formulation that uses simple matrix multiplication and convolution operations, making the system tractable for numerical optimization.
3Manufacturing precision
If PNS assessment is performed repeatedly during numerical optimization, then manufacturing precision is improved through iterative optimization, but loss of time worsens because each full simulation takes multiple hours
Solution Approach 1:
The patent uses a simplified linear PNS predictor as a copy of the full neurodynamic model's prediction capability. This surrogate model enables repeated evaluations during numerical optimization with millisecond computation time, allowing hundreds or thousands of iterations to complete in minutes rather than weeks, while maintaining sufficient accuracy for finding optimal coil designs.
Solution Approach 2:
The patent performs preliminary computation of the P-matrix before the optimization process. This precomputation stores all the necessary influence coefficients that will be needed during repeated assessments, allowing the optimization algorithm to rapidly evaluate different coil configurations by simple matrix operations without repeating the full simulation setup and computation each time.
Data Source
AI summary
A method for assessing peripheral nerve stimulation (PNS) for a coil geometry includes retrieving a PNS Huygens' P-matrix for a body model. The PNS Huygens' P-matrix is defined on a Huygens' surface enclosing the body model. The method further includes generating a coil specific PNS P-matrix for the coil geometry based on at least the PNS Huygens' P-matrix for the body model, determining at least one PNS threshold for the coil geometry based on the coil specific PNS P-matrix, and storing the at least one PNS threshold in a storage device.


