Sim4Life Release V5.2

The unstructured finite element method (FEM) low-frequency solver, which we released with Sim4Life V5.0 in June, has been received with great excitement by the community. Sim4Life V5.2 includes a new robust octree-based adaptive meshing engine that has the power to mesh highly complex surface-based structures such as the anatomical models of the Virtual Population. From now on, low-frequency simulations with Duke and Ella can be performed with only few limitations!

Further, Sim4Life V5.2 is now also compatible with Python 3, adding the latest features for automatization of evaluations requested by our numerous power-users.

Our 5G Simulation Toolbox has also been enhanced with a new total exposure ratio (TER) evaluator that allows the cumulative exposure of all frequency bands operating between 100 kHz – 110 GHz to be assessed according to the latest draft of the IEC/IEEE standard series.

More good news: IMAnalytics now also supports Tier 2 evaluations by providing owners of the MRIxViP field library with a streamlined and reproducible workflow for extracting field data in customized regions of interest, with derivation of all statistics necessary for Tier 2 of ISO/TS 10974.

Finally, V5.2 includes new productivity features and improvements as well as bug fixes, making your simulations more effective.

Feedback, as always, is warmly welcomed – we listen!

Unstructured LF FEM Solver – New Powerful Mesher

NEW OCTREE-BASED MESHER

• In Sim4Life V5.2 we are providing a new robust octree-based adaptive meshing approach, which is able to compromise between mesh resolution and geometrical accuracy with respect to the original computer-aided-design (CAD) objects.
• It is particularly suited to mesh very complex surface-based models, such as ViP models, with their large range of scales from thin and elongated structures to large organs like the lungs or poor-quality stereolithography (STL) files obtained from external sources.
• In particular, to create an unstructured mesh from complex anatomical models, the new mesher is superior to common schemes – especially for bottom-up meshing approaches, whereby sharp features are first meshed, then surfaces, then the interior is filled with volumetric elements, but the last step often fails if the surface contains self-intersections. 
• In hybrid mode, the new octree mesher in V5.2 can embed an unstructured mesh of objects, which requires accurate representation of sharp features and/or topology (e.g., medical devices or coils). Hybrid mode brings together two very different approaches, merging the key benefits of the bottom-up and the octree mesher.

Low-frequency simulation of a defibrillator placed on the Duke ViP model with the new Sim4Life V5.2 mesher: to save computational resources, very coarse resolution is used by the unstructured tetrahedral mesh in the background medium and in regions of the model far from the electrodes.

Low-frequency simulation of a defibrillator placed on the Duke ViP model with the new Sim4Life V5.2 mesher: a region including the heart was refined to sub-millimeter resolution, allowing accurate computation of the amount of current flowing through the heart.

Neuronal Dynamics Simulation

NEW FIBER MODELS: SMALL MRG FIBER

• Due to the increased demand to model mechanisms of deep brain stimulation (DBS) [1] and non-invasive brain stimulation (NIBS), a new parameterized electrophysiological model of myelinated fibers has been added to the library of electrophysiological models in T-NEURO in Sim4Life V5.2 according to the well-established McIntyre, Richardson, and Grill (MRG) parameterization [2].
• This model is largely used to characterize the neuroelectric response to stimulation of fibers of passage, cortico-spinal tracts, and white matter tracts, with diameters below 2 µm.

[1] Miocinovic S, Parent M, Butson CR, Hahn PJ, Russo GS, Vitek JL, and McIntyre CC. Computational analysis of subthalamic nucleus and lenticular fasciculus activation during therapeutic deep brain stimulation. J Neurophysiol. 96(3): 1569–1580, 2006.

[2] McIntyre CC, Mori S, Sherman DL, Thakor NV, and Vitek JL. Electric field and stimulating influence generated by deep brain stimulation of the subthalamic nucleus. Clin Neurophysiol. 115(3): 589–595, 2004.

IMAnalytics Enhancements

SUPPORT FOR TIER 2 OF ISO/TS 10974

• IMAnalytics in Sim4Life V5.2 can now extract and process even more information from simulated magnetic resonance imaging (MRI) electromagnetic field (EMF) libraries, such as MRIxViP.
• New features in the Python API allow users to extract field data limited to regions of interest of arbitrary shapes and to perform customized statistics across the whole field database.
• An example notebook that shows how to compute and aggregate results in the region occupied by a pacemaker is provided. Used with realistic and validated input data such as the complete MRIxViP library, the same notebook provides a systematic, customizable, and reproducible way to compute all the statistics necessary for the Tier 2 of ISO/TS 10974.

Safety assessment of a generic pacemaker: EMF at the location of the implant (padded with a 10% position uncertainty margin) are extracted from the whole MRIxViP field library using the IMAnalytics Python notebook. Statistical distributions of 10g-averaged electric fields are computed at normal operating mode for each anatomical model. 

Extended ViZoo

NEW ANIMAL ANATOMICAL MODELS

• Sim4Life V5.2 users are provided with a new rat anatomical model that extends the ViZoo family and provides unprecedented details in the peripheral nervous system (PNS), connectivity to organs and muscles, and functionalization with compartmental nerve models to investigate interactions with neuronal electrophysiology.
• The whole-body rat model was segmented from co-registered high-resolution (80 × 80 × 80 µm) MRI and computed tomography (CT) images.
• In a forthcoming version (Q1/2020), the model will further include posing functionality and detailed segmentation of the vagus nerve.
• The new rat model is uniquely detailed for animal experimental studies and, together with the human models, is expected to have a major influence on computational neuro-electrophysiology research. 

New rat model as part of ViZoo with unprecedented level of detail in the PNS, connectivity to organs and muscles, and functionalization with compartmental nerve models to investigate interactions with neuronal electrophysiology, available in Sim4Life V5.2: bones and major internal organs have been segmented from co-registered MRI and CT images.

Unrivaled 5G Simulation Toolbox: Important New Features

mmWAVE COMPLIANCE ASSESSMENT: TOTAL EXPOSURE RATIO

• Sim4Life V5.2 features an extension that is of particular importance to mobile device engineers – the total exposure ratio (TER) evaluator.
• For devices that have multiple EMF emission sources, regulators require that overall exposure is assessed by considering all sources simultaneously.
• It is not sufficient for each radiative source to comply with the limit effective at its operating frequency: the TER for the device must be <1. The TER combines exposure ratios of multiple antennas, from DC to mmWave frequencies.
• Being able to compute the TER easily in a direct manner in Sim4Life V5.2 allows engineers to keep the big picture in mind and integrate overall exposure assessment early in the design phase of the device.

TER extension combining exposures of a WiFi antenna at 2.4 GHz (1g-averaged specific absorption rate) and a mmWave antenna array at 25 GHz (1 cm²-averaged power density) in Sim4Life V5.2.

mmWAVE COMPLIANCE ASSESSMENT: POWER DENSITY EVALUATORS 

• In line with our commitment to be always at the forefront of regulatory activities, Sim4Life’s 5G Toolbox power density (PD) evaluators are ahead of the curve, with the latest requirements from regulators already integrated.  
• In Sim4Life V5.2, a new conservative algorithm for surface-averaging of PD on flat surfaces, which is required in the latest IEC/IEEE 63195-2 standard draft, has been implemented and is now the default option for PD computation.
• Averaging is performed by rotating a square averaging area by increments of 5° at every point on the evaluation surface and recording the maximum value of PD found at each point.
• Formerly used averaging algorithms, which are useful for obtaining a quick estimate in cases where strict compliance with standards is not necessary, remain available to users.

PD near a mmWave antenna array operating at 25GHz, surface-averaged following latest IEC/IEEE 63195-2 standard draft. The highest power density is recorded near the second sub-array when the 1cm² averaging square is at a 45-degree angle.

Collaboration and Productivity Tools

COLLABORATIVE EXCHANGE OF CONFIDENTIAL MODELS

• Until now, only the Virtual Population models of the IT'IS Foundation could be shared as licensed models. In Sim4Life V5.2, we have now extended this feature to empower third parties to share models without disclosing confidential content. If interested, please request more detailed information and a license at s4l-sales@zmt.swiss.

AVAILABILITY OF PYTHON 3

• Sim4Life V5.2 now provides users with upgraded Python 3 support and an application program interface (API) to meet the requirements of the market and to keep up with the latest generation of Python 3.
• Python 2.7 has reached its end-of-life (EOL), thus and community support will be discontinued. With the addition of Python 3, Sim4Life’s Python API is future-proof.
• Until further notice, Python 2.7 will also still be supported by Sim4Life to guarantee backwards compatibility of user scripts and a smooth transition to the newer versions.

A more comprehensive list of improvements, new features, and fixes is included in the Release Notes.

To experience the power and elegance of Sim4Life V5.2 or for further information, please email us at s4l-sales@zmt.swiss or call us at +41 44 245 9765.

The relevant Sim4Life installers for Win7/Win8/8.1/Win10 64-bit platforms can be downloaded here. Existing customers with an up-to-date annual maintenance and support plan, will receive individually all pertinent information regarding the Software Installer Download and updated licenses.

At ZMT we are committed to support our customers with the most innovative software solutions, testing equipment, and service.

The Sim4Life Team