Rapid PNS Threshold Prediction for MRI Gradient Coil Design

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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

VSEngineering 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

Engineering Contradiction:
ImprovePNS threshold prediction accuracyVSAvoidassessment speed
Core Design Contradiction:
Measurement precisionVSProductivity

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.

Inventive Principle:
Principle #26Copying

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.

Inventive Principle:
Principle #10Preliminary action

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

Engineering Contradiction:
ImprovePNS threshold prediction accuracyVSAvoidmodeling framework complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

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.

Inventive Principle:
Principle #2Taking out (Extraction)

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.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Engineering Contradiction:
Improvecoil design optimization precisionVSAvoidtotal optimization time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

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.

Inventive Principle:
Principle #26Copying

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.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS12268508B2System for and method of rapid peripheral nerve stimulation assessment of gradient coils
Publication Date: 2025.04.08 THE GENERAL HOSPITAL CORP
  • US12268508B2 patent drawing
  • US12268508B2 patent drawing
  • US12268508B2 patent drawing

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.