Sim4Life Release V6.2

ZMT has deployed a new release of its Sim4Life platform. V6.2 not only comes with a smoother look and feel and a better user experience but also with important new features, refinements, and bug fixes.

New features include:

• Neuromodeling: a more than 40-times faster  T-NEURO postpro algorithm that allows simulations of complex neural circuitry on a desktop workstation in minutes
• NeuroRat V4.0: the first neuro-functionalized animal model for neuro-electrophysiology simulations that can be posed and features detailed nerve trajectories 
• IMAnalytics V4.0: GUI overhaul, and support for Test Field Diversity measurements of implants with the MRIxLAB phantom field library
• 5G Transmitter Design and Evaluation: user-defined codebooks (incl. phase configuration uncertainty) is part of our Maximum Exposure Optimizer which now supports synchronized features with DASY8/6 Module mmWave and full compatibility with FDIS of IEEE/IEC 63195-1 and 63195-2
• IP protection: effective collaboration while protecting intellectual properties (IP) of key active and passive components based on a unique Huygens source feature; we are proud to announce that we will extend this solution in the next release to not requiring IP protected simulation models of 3rd party modules but instead importing measured fields, i.e., model validation will become unnecessary and the simulation uncertainty will be even lower.

Additional highlights of our V6.2 release include a new toolbox to generate implant routings for magnetic resonance imaging (MRI) safety evaluations, enhanced functionality for simulating induced electric fields from measured data (DASY8/6 Module WPT) , and an improved VSCode/Python 3 extension.

Feedback, as always, is greatly welcome – we listen!

Neuronal Dynamics Simulation

POSTPRO CONVERSION: >40X SPEEDUP

In Sim4Life V6.2, the T-NEURO module comes with a huge performance boost that results in speedups of 40 times and more.

• Optimizations to Sim4Life’s neuronal dynamics post-processing conversion algorithms offer a massive speedup in time-to-solution, unlocking the power to perform longer and more complex simulations of neural dynamics. 
• Post-processing 10 ms of simulated activity in ~1000 neurons is now possible in just 16 seconds, a calculation that previously required >10 minutes!
• This enhancement enables simulations of complex neural circuitry (such as the spinal cord circuit with branching rootlets depicted below) that were formerly impossible without access to dedicated computing resources. Other potential applications include complex multi-fascicular nerves with high-density distributions of myelinated and unmyelinated fibers, and MRI safety evaluations using whole-body nerves of various types and axonal diameters.

ADDITIONAL IMPROVEMENTS

• The integration of Yale’s NEURON simulation environment directly into Sim4Life’s T-NEURO solver offers the flexibility to make use of external solvers to run simulations, allowing for batching and automated resource management. 
• Spike locations in titrations are now represented as dimensionless points instead of fixed-radius spheres for easy visualization.

MRI Safety Assessment

PREANNOUNCEMENT OF IMANALYTICS V4.0

Sim4Life V6.2 is ready for IMAnalytics V4.0! The IMAnalytics V4.0 Module will be released end of April/mid-May together with the MRIxLAB phantom field dataset from the IT’IS Foundation with important new features:

• Using the MRIxLAB dataset of pre-computed induced fields in the Test Field Diversity (Yao et al 2020) phantom, IMAnalytics V4.0 predicts the ISO 10974 Tier 3 in vitro deposited power or induced voltage for different test routings, incident field polarizations and tissue-simulating media, making the experimental transfer function validation process faster and error-proof.
• Streamlined graphical user interface (GUI) to improve the overall user experience: the tabs are removed and all tools are available from the main windows. Jupyter notebooks can be launched directly from the main interface.
  
• Computation of Tier 3 induced voltage induced is available from the GUI of IMAnalytics, and no longer requires the use of Jupyter notebooks. 
• Exported results contain all plots, raw data, and study parameters used, all packaged into a single zip file, for full traceability and easy archiving.  

NEW WIRE MODELING TOOLS & ROUTINGS TOOLBOX

Sim4Life V6.2 features new wire modeling tools and functions that are powerful for creating implant routings or generally for working with wires (e.g., nerve trajectories).

• The Routings Toolbox supports MRIxViP users to generate implant routings for MRI safety evaluations
• V6.2 features new functionality to split wires, re-orient (large) number of wires and to approximate wire(s) by re-parameterization of splines and polylines with a specified number of handles.
• Furthermore, the “Create Loops Tool” can extend an existing routing trajectory with specified length and radius when being positioned on a reference surface (e.g., to place loops on muscle or subcutaneous adipose tissue (SAT) surface).
  
• The Routings Toolbox is actively used at IT’IS to create/edit neuro-functionalized nerve trajectories (for instance for the upcoming nerve trajectory extensions in Yoon-sun V4.1 and Jeduk V4.1).

Sim4Life V6.2. Routings Toolbox in action in a nerve trajectory model of NeuroRat V4.0.

5G Simulation Toolbox Enhancements

5G SIMULATION TOOLBOX AND mmWAVE COMPLIANCE ASSESSMENT

In Sim4Life V6.2, numerous powerful enhancements have been added to the power density evaluators and post-processing of the 5G Simulation Toolbox.

• The Power Density Evaluator has been updated to the latest version of the IEEE/IEC 63195-2 and 63195-1 standards; it includes minor changes in the naming of the different averaging definitions and additional features such as the ability to perform square-like averaging on curved surfaces.
• The Power Density Evaluator can now automatically pad the input fields with zeros, to be fully consistent with the DASY8/6 system.
• The Maximum Exposure Optimizer (MEO) now supports user-defined codebooks. Multiport simulation results of phased arrays that operate under a known list of phase configurations (i.e., with a codebook) can be used to quickly determine the maximum peak surface-averaged power density (mpsPD) across all configurations. Using an exhaustive search approach, the algorithm determines the mpsPD following the latest version of the IEEE/IEC 63195-2 standard, with no over-estimation.
• Codebooks that carry some uncertainty on the actual phase configurations achieved by the device (phase shifters are never ideal!) can still be used with MEO. Optimization methods will be used to search for mpsPD within the range of uncertainty of each configuration.
• Since the release of Sim4Life V6.0 and SEMCAD X V19.0 DASY8/6 measurements of phased arrays can be easily imported. In Sim4Life V6.2 and SEMCAD X V19.2, the algorithm that reconstructs absolute phase references of each independent measurement, so far only available for the DASY8/6 system, is also available. This makes the interoperability between the two measurement and simulation systems complete and seamless.

5G Simulation Toolbox in Sim4Life V6.2: Maximum peak power density mpsPD is computed across all 55 configurations of the codebook of a 25 GHz validation device.

Solvers: Important New Features

IMPORT/EXPORT HUYGENS SIMULATIONS FOR ENHANCED COLLABORATION

Sim4Life V6.2 adds an important feature to export/import a simulation field sensor and use it as a Huygens source to simulate exposure scenarios, e.g., by including dedicated phantoms.

• Electromagnetic fields of any finite-difference time-domain simulation can now be exported as a standalone Huygens source file. The resulting file contains field data in a chosen field sensor and can be reused in any other project as an incident field source for a Huygens simulation.
• This feature makes it easy to split simulations of source fields (e.g., coils or antennas) and exposure scenarios (e.g., phantoms or anatomical models) into several independent Sim4Life/SEMCAD X projects.

Sim4Life V6.2 Huygens field export/import in action (5G, compliance):Project 1: full-wave simulation of fields radiated at 28 MHz by 5G phone with results exported as Huygens file; Project 2: power density absorbed by head phantom using Huygens file as incident field.

Sim4Life V6.2 Huygens field export/import in action (MRI, compliance): Project 1: full-wave simulation of 1.5T MRI coil, with fields inside region-of-interest exported as Huygens file; Project 2: specific absorption rate from induced currents inside Virtual Population model Duke using Huygens file as incident field.

WPT Compliance Assesment

INTEROPERABILITY ENHANCEMENTS: SIM4LIFE - DASY8/6 MODULE WPT & MAGPy

Since the release of V6.0, Sim4Life allows to import measured magnetic fields from DASY8/6 Module WPT and use these to simulate the induced electric field and peak spatial specific absorption rate (SAR) inside a conductive phantom. In Sim4Life V6.2, important functionality enhancements have been added:

• The imported magnetic fields measured with the MAGPy probe used in DASY8/6 Module WPT can now be extrapolated to "infinity" on all sides.
• This enables large Virtual Population (ViP) model simulations by avoiding boundary effects during the Magneto-QuasiStatic (MQS) simulations – and thus supporting large real-world computations by feeding your measured data to Sim4Life’s MQS solver.

Simulation of SAR from currents induced in Virtual Population model Duke by a WPT charging coil; magnetic field measurement are imported from the MAGPy probe of DASY8/6 Module WPT into Sim4Life V6.2.

Extended ViZoo Library

NEW ANIMAL MODELS

• The new NeuroRat V4.0 is the first animal model with peripheral nerve trajectories for neuro-electrophysiology simulations for use with the T-NEURO module of Sim4Life.
• The model includes detailed segmentation of bones and of all major organs, is posable and fully compatible with the IT'IS material properties database.
• For non-commercial purposes, the model can be complemented with a co-registered version of the Waxholm Space Atlas of Sprague Dawley Rat Brain.