Draft:Virtual Population

The Virtual Population (ViP) is a set of computational human and animal models developed by the Foundation for Research on Information Technologies in Society (IT'IS) in collaboration with the US Food and Drug Administration (US FDA). The platform is managed by the IT'IS Foundation, an independent non-profit research institute based in Zurich, Switzerland, dedicated to advancing computational modeling of biological tissues. The ViP models are an integral part of the Sim4Life computational simulation platform developed by ZMT Zurich MedTech AG (ZMT) in Zurich, Switzerland, in partnership with IT'IS.

Overview

The ViP is made up of computational models that can be used in research across various scientific and medical fields. The models facilitate the simulation of physical interactions with biological tissues, supporting applications such as wireless device development, medical device development, radiological safety assessments, and tissue engineering research. The models include representations of whole-body computational phantoms and specific body regions of humans as well as computational phantoms of animals and animal tissues of species typically used in medical research.

The IT’IS Foundation also maintains a database of tissue properties to provide the computational life sciences community with values for electromagnetic (EM), thermal, fluid, acoustic, and magnetic resonance imaging (MRI) properties of biological tissues. The database was developed from published resources and is continually updated. Users can import the material database into the Sim4Life simulation software platform and automatically assign tissue parameter values to the ViP models.

Development

The development of the ViP models began with the creation of four surface-based anatomically correct whole body human models of a 34-year-old adult male, a 26-year-old adult female, an 11-year-old girl, and a 6-year-old boy – originally referred to as the Virtual Family – for evaluation of EM exposure in different age groups and body types. The "Version 1.x" models were based on high resolution magnetic resonance imaging (MRI) data of healthy volunteers and are provided to the scientific community free-of-charge.

Subsequent advancements led to the development of higher-resolution, multi-organ models and an expansion of the Virtual Family to the Virtual Population with more models of both sexes ranging in age from 5 to 84 years old. In addition to providing broader population coverage, the ViP enhanced models are suitable for evaluation of the safety of diagnostic and therapeutic applications, including assessments of medical implant safety.

The ViP models were upgraded with the physics-based "Poser" method, implemented in Sim4Life, which allows the posture of the models to be altered via finite element method (FEM) simulations, wherein the body is treated as a deformable hyperelastic material with rigid bones.

A further upgrade to the ViP models was to make the models morphable, to simulate how an individual would gain or lose weight through changes in the distribution of subcutaneous adipose tissue (SAT). The changes in the SAT volume elastically deform the surrounding tissues but are constrained by rigid bones. The morphing capability effectively broadens the body mass index (BMI) distribution of the ViP models.

Certain applications in computational life sciences require access to high precision models of specific organs. The IT’IS Foundation in collaboration with the US FDA developed the MIDA, a detailed computational anatomical model of the head and neck, and four additional head models – the IXI Head Models – segmented from the IXI dataset, a public multi-modal MRI collection include detailed representations of eyes, deep brain structures, scalp layers, blood vessels, and salivary glands. The ViP hand library is a set of 12 computational right hands of different sizes and ages extracted from the full-body ViP models. Additionally, the Ella Breast Coil model is a modified version of Ella created for specific applications, such as safety assessments and the design of specialized MRI coils. The IT'IS Foundation also hosts the Breast Tumor Patient Models (BTPM) Repository, a collection of 22 unique breast models developed at the Erasmus University Medical Center that are segmented into segmented into 6 tissues: skin, bone, muscle, tumor, fibroglandular, and fat.

Korean models – male model Jeduk and female model Yoon-sun – were developed by the IT’IS Foundation and Visible Korean Human (VKH) teams in the Swiss-Korean collaborative project "NEUROMAN: Functionalized Anatomical Models for Studying EM-Neuronal Dynamic Interactions". The VKH models, which are based on serial sections of whole cadavers to produce cross-sectional slices compiled into 3D images, were developed for in silico studies of the interactions of neurons with EM fields and include detailed nerve segmentation. The ViP model Eddie is also based on high-resolution cryosection images, in this case obtained from the Visible Human Project of the US National Library of Medicine (NLM).

ViP human models

Many of the ViP human models were given the first names of jazz musicians. The specifications of the full-body human models are listed here.

Model	Sex	Age (y)	Height (m)1	Weight (kg)1	BMI (kg/m²)1	Model namesake
Duke	male	34	1.77	70.2	22.4	Duke Ellington
Ella	female	26	1.63	57.3	21.6	Ella Fitzgerald
Billie	female	11	1.49	34.0	15.3	Billie Holiday
Thelonious	male	6	1.16	18.6	13.8	Thelonious Monk
Glenn	male	84	1.73	61.1	20.4	Glenn Miller
Fats	male	37	1.82	119	36	Fats Waller
Louis	male	14	1.68	49.7	17.6	Louis Armstrong
Eartha	female	8	1.36	29.9	16.2	Eartha Kitt
Dizzy	male	8	1.37	25.3	13.5	Dizzy Gillespie
Roberta	female	5	1.09	17.8	14.9
Nina2	female	3	0.92	13.9	16.4	Nina Simone
Charlie2	female	8 weeks	N/A	4.3	N/A	Charlie Parker
Pregnant woman I2,3	N/A	3 months (in utero)	N/A	0.015	N/A
Pregnant woman II2,3	N/A	7 months (in utero)	N/A	1.4	N/A
Pregnant woman III2,3	female	9 months (in utero)	N/A	2.7	N/A
Jeduk	male	33	1.62	64.5	24.6
Yoon-sun	female	26	1.52	54.6	23.6
Eddie	male	38	1.81	106.0	32.4

¹ Height, weight, and BMI values are based on the latest versions of the models and of the tissue properties database. ² These models are available only as Version 1.x. ³ The pregnant woman models are based on the Ella model; the specifications listed are those of the fetus.

The IT'IS Foundation also hosts computational anatomical models developed by other researchers.

Animal models

In addition to the human computational models, the IT'IS Foundation also developed the Virtual Zoo (ViZoo) models – a set of detailed high-resolution anatomical animal models created from MRI or cryosection image data. Computational animal phantoms can be used in in silico biophysical simulations to reproduce and analyze results from in vivo animal experiments, with the goal to reduce the need for experimentation on laboratory animals. The ViZoo models include mice and rats of both sexes at various stages of development, a male pig, and a female Rhesus macaque (developed as part of the NEUROMAN project). A special rat model with neuro-functionalized nerve trajectories – the NeuroRat – has also been released.

Name	Sex	Type	Length (mm, without tail)	Weight (g)
"Miss Able" Female Monkey	female	Rhesus macaque	740	4900
Male Pig	male	Domestic Pig	977	35000
NeuroRat	male	Dark Agouti	150	150
Big Male Rat	male	Sprague Dawley	260	567
Small Male Rat	male	Sprague Dawley	185	198
Female Rat with Tumors	female	Sprague Dawley	225	503
Pregnant Rat	female	Sprague Dawley	170	275
Rat Pup	undefined	Sprague Dawley	93 (with tail)	14.3
Male PIM1 Mouse	male	PIM1	98	44.7
Male OF1 Mouse	male	OF1	95	35.5
Female OF1 Mouse	female	OF1	78	17.3
Pregnant Mouse	female	B6C3F1	72	28.7
"Diggy" Male Nude Normal Mouse	male	Nude Normal	86	28
Pregnant Mouse	female	C57BL/6N	160	38
3 Week Male Mouse	male	B6C3F1	70	12.3
12 Week Female Mouse	female	B6C3F1	80	22.3
12 Week Male Mouse	male	B6C3F1	90	27.4

External links

• Zurich MedTech AG website
• Virtual Population Overview page at the IT'IS Foundation website