Tensor field mapping with magnetostatic constraint

A non-transitory computer-readable storage medium for use in conjunction with a computer system, the computer-readable storage medium configured to store program instructions that, when executed by the computer system, cause the computer system to perform operations comprising:

• applying, to a sample, an excitation using a source, wherein the excitation comprises or corresponds to one or more of:
• electromagnetic radiation, a radio-frequency wave, a particle beam, a sound wave, a magnetic field, or an electric field;
• measuring, using a measurement device, a response associated with the sample to the excitation;
• computing, using an inverse model or a predetermined predictive model, which has the measured response and information specifying the excitation as inputs, model parameters on a voxel-by-voxel basis in a forward model with multiple voxels that represent the sample,
• wherein the predetermined predictive model was trained, prior to the applying and the measuring, using training data for different excitation strengths, different measurement conditions or both,
• wherein the model parameters comprise magnetic susceptibilities of the multiple voxels,
• wherein the forward model simulates response physics occurring within the sample to the excitation, and
• wherein the forward model is a function of the excitation, the model parameters of the multiple voxels, and differential or phenomenological equations that approximates the response physics;
• determining, using a computer, an accuracy of the model parameters by comparing at least the measured response and a calculated predicted value of the response using the forward model, the model parameters and the excitation;
• and
• providing, when the accuracy exceeds a predefined value, the model parameters to an electronic device, to a display or to memory.

A system, comprising:

• a source configured to provide an excitation, wherein the excitation comprises or corresponds to:
• electromagnetic radiation, a radio-frequency wave, a particle beam, a sound wave, a magnetic field, or an electric field;
• a measurement device configured to perform measurements;
• a computation device, coupled to the source, the measurement device and memory, configured to execute program instructions;
• and
• the memory, coupled to the computation device, configured to store the program instructions that, when executed by the computation device, cause the system to perform operations comprising:
• applying, to a sample, the excitation using the source;
• measuring, using the measurement device, a response associated with the sample to the excitation;
• computing, using an inverse model or a predetermined predictive model, which has the measured response and information specifying the excitation as inputs, model parameters on a voxel-by-voxel basis in a forward model with multiple voxels that represent the sample,
• wherein the predetermined predictive model was trained, prior to the applying and the measuring, using training data for different excitation strengths, different measurement conditions or both,
• wherein the model parameters comprise magnetic susceptibilities of the multiple voxels,
• wherein the forward model simulates response physics occurring within the sample to the excitation, and
• wherein the forward model is a function of the excitation, the model parameters of the multiple voxels, and differential or phenomenological equations that approximates the response physics;
• determining, using the computation device, an accuracy of the model parameters by comparing at least the measured response and a calculated predicted value of the response using the forward model, the model parameters and the excitation;
• and
• providing, when the accuracy exceeds a predefined value, the model parameters to an electronic device, to a display or to the memory.