Solvers and Tissue Models

Electromagnetics Full Wave Solvers

The Electromagnetics Full Wave Solvers (P-EM-FDTD) provide accelerated full-wave EM modeling (> 1 billion voxels) on adaptive, inhomogeneous meshes and a unique multi-resolution subgridding algorithm for optimal local mesh refinement. The solvers support dispersive materials, thin layer models, conformal corrections, lumped circuit element modeling, and a rich set of boundary conditions and source types. Furthermore, they offer accurate and efficient skin models for mm-wave applications, and are powerful enough to handle the full complexity of our Virtual Population anatomical models.

Application Areas

  • EM system modeling and optimization
  • Biomedical device design and optimization
  • Antenna and antenna array design, placement optimization, link budgets
  • Wireless power transfer (WPT) systems
  • Wireless communication device design
  • Radar
  • Impedance, cross-talk, interference
  • In-to-in and on-to-in body link optimization
  • Exposure assessment (incident E- / H-fields, iPD, induced fields, SAR, APD, ΔT, ICNIRP and IEEE exposure standard metrics)
  • MRI system (pTx RF coils, Rx RF coils) coil design
  • MR exposure safety (including active and passive implants)
  • RF/MW hyperthermia
  • RF tumor ablation

Quasi-Static Electromagnetic Solvers

Sim4Life’s structured Quasi-Static Electromagnetic Solvers (P-EM-QS) and their unstructured counterparts (P-EM-UQS) enable efficient modeling of static and quasi-static EM regimes by applying the finite element method on graded voxel-based and unstructured meshes. The solvers support message passing interface (MPI) parallelization, and offer optimized performance in terms of accuracy and speed over a wide range of EM regimes. The P-EM-QS family of solvers is ideal for handling heterogeneous, complex geometries, while the P-EM-UQS family of solvers provides superior discretization of fine features in CAD-based geometries.

Applications Areas

  • EM modeling and optimization in low-frequency and static regimes
  • Biomedical device design and optimization
  • Wireless power transfer (WPT) systems
  • Impedance, cross-talk, interference
  • In-to-in-body and on-to-in-body link optimization
  • Exposure assessment (support for LF exposure metrics from international standards on exposure safety)
  • Low frequency risk assessments (WPT, MR gradient coils, welding, induction cookers, etc.)
  • Non-invasive neurostimulation optimization (TMS, TES, temporal interference stimulation (TIS))
  • Implanted neurostimulation optimization (DBS, SCS, pacemakers, etc.)
  • Neuroprosthetics (retinal, cochlear, vestibular, motor prosthetics)
  • Bioelectronic medicine and ‘electroceuticals’ (modulation of peripheral nervous system to restore/control organ physiology and the immune system)
  • Brain-machine interfaces (BMI)
  • EEG/ECG
  • Neural sensing for closed-loop controlled, state-synchronized therapies and diagnostics
  • MRI gradient coil design
  • Low-frequency hyperthermia (e.g., with nanoparticles)

Thermodynamics Solvers

The Thermodynamics Solvers (P-THERMAL) enable the modeling of heat transfer in living tissues using advanced perfusion and thermoregulation models. The solvers include a finite-difference time-domain (FDTD) and a steady-state finite volume solver. Both structured, rectilinear voxel discretizations (ideal for heterogeneous systems and/or complex geometries) and unstructured meshes (good for highly accurate representations of fine CAD structures) are supported. Exclusive thermal damage and effect quantification models (e.g., T-CEM43 thermal dose) are included.

Applications Areas

  • Thermal management
  • MRI Tx RF coil design and safety assessments
  • MRI safety of active and passive Implants
  • RF thermal therapies (e.g., hyperthermic oncology)
  • Safety and efficacy evaluation of ultrasonic therapeutic devices
  • RF/MW tumor ablation, RF surgery
  • Cryosurgery, brain cooling
  • MRgFUS neurosurgery applications (tumor ablation, neuropathic pain treatment, movement disorders)
  • Hypothermia and heat stroke
  • Temperature-dependent neuronal dynamics
  • Local cooling by large vessels and perfusion

Acoustic Solver

The full-wave Acoustics Solver (P-ACOUSTICS) handles linear and non-linear pressure waves (dispersive properties, frequency mixing). It is optimized for computing the propagation of pressure waves through complex environments such as the human body, or highly heterogeneous media like the skull. Furthermore, the Acoustics Solver supports CT-based bone property maps to enable personalized focused ultrasound targeting.

Application Areas

  • Acoustic exposures
  • High- and low-intensity focused ultrasound (HI/LIFUS)
  • Design and optimization of diagnostic and therapeutic ultrasound devices
  • Safety and efficacy evaluations of ultrasound devices
  • FUS-based reversible blood-brain barrier disruption for the targeted enhancement of active agent delivery
  • Ultrasound-mediated drug release
  • Acoustic neuromodulation
  • MRgFUS neurosurgery (tumor ablation, neuropathic pain treatment, movement disorders, etc.)

Neuronal Tissue Models

The Neuronal Tissue Models (T-NEURO) enable dynamic modeling of EM-induced neuronal physiology, from activation to inhibition, using multi-compartmental representations or generic models. Sim4Life integrates Yale University’s NEURON simulation environment, which is ideal for studying field-neuron interactions, optimizing neurostimulation devices, and assessing exposure safety. T-NEURO goes beyond the prediction of individual axonal responses – its unique implementation of the extended reciprocity theorem permits the simulation and analysis of whole-brain biosignals such as magneto-/electroencephalography (MEG/EEG), accommodating realistic neuronal sources, inhomogeneous dielectric environments, and various recording device geometries.

Application Areas

  • EM neurostimulation (spinal cord stimulation (SCS), deep brain stimulation (DBS), etc.)
  • Transcranial brain stimulation (electrical: transcranial alternating/direct current stimulation (TACS/TDCS), temporal interference stimulation (TIS); magnetic: transcranial magnetic stimulation (TMS))
  • Neural sensing (compound action potentials (CAP), electroencephalogram (EEG) and electrocorticogram (ECoG) recordings, local field potentials (LFP), etc.)
  • Catheter-based stimulation and sensing
  • Neuroprosthetics (retinal, cochlear, vestibular, motor prosthetics)
  • Bioelectronic medicine (‘electroceuticals’)
  • Magnetic resonance-guided focused ultrasound (MRgFUS) neurosurgery (tumor ablation, neuropathic pain treatment, movement disorders, etc.)
  • Low frequency EM exposure safety assessment (wireless power transfer, MR gradient coils, etc.)
  • Temperature-dependent neuronal dynamics
  • Neuro-motoric incapacitation
  • Neural interface design and optimization
  • Brain-machine interfaces (BMI)

Thermal Tissue Damage Model

Thermal Tissue Damage Model

Sim4Life’s thermal dose and tissue damage models permit assessment of the impacts of heating on the physiology of living tissues. The CEM43 tissue heating model is a widely applied technique for quantifying the effects of transient heating based on direct, cytotoxic effects. CEM43 converts time-varying thermal exposures into an equivalent exposure time (in minutes) at 43°C. The approach permits quantitative comparisons of different transient heat exposure scenarios (e.g., short heating at high temperature vs. prolonged, moderate heating) by relating them to an established damage threshold. Sim4Life also provides direct assessments of tissue damage through the Arrhenius tissue damage model.

Application Areas

  • Hyperthermic oncology (efficacy evaluation and optimization)
  • Radiofrequency, microwave, and focused ultrasound ablation
  • MR safety with and without implanted devices
  • Electromagnetic and thermal exposure safety
  • Skin burn quantification

Database of Tissue Properties

The material parameter database, originated and maintained by the IT’IS Foundation, provides the computational life sciences community with recommended values for, and associated variances of, a growing list of biological tissue properties. The database is free, online accessible, and continually updated to reflect the highest quality measurements available. Sim4Life makes it easy for users to automatically assign tissue parameter values to the Virtual Population (ViP) models from the material properties database. In addition, Sim4Life supports image-based assignment of heterogeneous tissue property maps (anisotropic brain tissue conductivities, perfusion, acoustic propagation in bones) for enhanced realism and accuracy.

List of properties:

  • Frequency-dependent dielectric properties
  • Densities
  • Heat capacities
  • Thermal conductivities
  • Heat transfer rates
  • Heat generation rates
  • Viscosities
  • Acoustic properties (speed of sound, attenuation constant, and non linearity)
  • Tissue weight fractions
  • MR parameters (longitudinal and transversal relaxation times)

Perfusion Models

Perfusion is frequently the dominant factor influencing (and limiting) in vivo heating. Therefore, our thermal solvers offer advanced models of perfusion and vasculature, including active thermoregulatory processes known to affect perfusion rates.

Engineering Tools

IMAnalytics

IMAnalytics is a novel software platform solution for the comprehensive safety evaluation of implantable devices. The module uses the Tier 3 approach as defined in ISO 10974 to characterize RF-induced power deposition and heating at the distal electrodes of implantable devices, and the voltage at the lead terminals of the pulse generator. Furthermore, it extracts the RF-induced electric field in a region of interest for use in ISO 10974’s Tier 2 approach, or for calibrating ASTM F2182 phantom measurements. IMAnalytics and the IT'IS MRIxViP1.5T/3.0T field libraries are the first computational modeling-based Medical Device Development Tools (MDDT) approved by the FDA.

 

Phased-Array Antenna Tools

The Sim4Life Phased-array Antenna Toolkit provides the most efficient solution on the market for the design, analysis, and optimization of 5G mmWave antenna arrays. It empowers engineers to rapidly develop and study phased-array antennas to meet demanding performance requirements, including regulatory compliance. The power density algorithm is fully compliant with IEC/IEEE 63195 standards on both flat and curved surfaces.

Parameterized MRI Volume Coil Designer

The MRI Volume Coil Designer is an interactive tool to create birdcage-style volume coils according to user-specified design parameters including physical dimensions, operating frequency, feeding, and coil topology.

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