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Modelling and simulation in medicine, towards a digital patient

Sofa © Inria / Photo C. Morel

Medical imaging has transformed medicine by enabling the visualisation of the inside of the patient's body. Digital simulation in medicine makes it possible to go even further. 

By modelling the behaviour of the organs and interactions with therapeutic tools, it enables the creation of a digital clone of the patient, radically changing the way doctors train, prepare complex operations and carry out surgery. Some of these tools have already entered the realm of medical practice and interactive medical simulation has, for several years now, been recognised as an effective tool to assist learning in medicine. Today, there are almost 50 simulation centres in France, where medical staff practise on increasingly realistic simulators, without putting a patient at risk.  However, the impact of modelling and simulation in medicine extends to many other fields. By merging a 3D model of a patient created prior to the operation with images obtained as the surgery is taking place, the surgeon has the possibility of visualising structures that are usually invisible. This augmented reality illustrates the undeniable contribution of digital modelling to medical imaging. In the future diagnosis, surgical interventions and planning of the treatment of numerous illnesses will benefit from the contributions of digital simulation.  

Several of the Inria Nancy - Grand Est centre teams work on different aspects of this vast, multidisciplinary field. Thanks to this work, different organs have already been modelled: heart, liver, brain. These simulations are often based on multi-physical approaches (capable of integrating physiological or biomechanical parameters), adapting the characteristics of the model to the specificities of the patient (anatomy, elasticity, electrical diffusion, pressure, etc). For this, the researchers work on digital models and methods that are capable of providing the result of very complex calculations in just several hundredths of a second. Clinicians can, as a result, instantaneously visualise the potential impact of each of their acts. This work is carried out in collaboration with the region's hospitals and clinicians, and looks to go beyond the boundaries of academic research to be transferred to the clinical world. 

Its applications

The applications of this research work concern liver surgery, neurosurgery, retinal surgery, vascular surgery and interventional radiology. The simulation tools can intervene at different stages, from training to assistance in the operating theatre.  

Here are some examples:

  • Augmented reality for deformable organs.
  • Navigational assistance in vascular surgery via the real-time 3D modelling and simulation of the instruments.
  • Intra-operative assistance in mini-invasive surgery through the superposition of additional information.
  • Planning of neurosurgical interventions for deep brain stimulation. 

Sofa Framework, for real-time simulation targeting medical applications  

Major advances in medicine have been made possible through a better understanding of the human body. In this context, Sofa enables the reproduction through computation of the physics (mechanical, thermal or electric) and interactions between organs of the human body. As a result, it becomes possible to train doctors better and to help them during the planning of operations.  

Sofa is co-developed by several Inria centres and relies on an international community. A software consortium bringing together academic and industry partners has been put in place. With Sofa, the Inria Nancy - Grand Est centre teams focus more specifically on two research themes: developing "patient-specific" models reproducing the characteristics of a specific patient and improving the management of smart topological changes, i.e. modifications to the geometric representation of an object during computation. 
In addition, one version of the software (Sofa-OR) aims to assist the surgeon during operations on a human patient in a real operating theatre, using augmented reality.

The Sofa platform came from the idea of creating an open source infrastructure for the 
simulation of complex physics phenomena such as the deformation of soft materials. Today, Sofa aims to simulate other physics phenomena such as thermodynamics or fluid mechanics. Numerous functionalities have been introduced with, among others, many solvers, physics models (such as non-linear elasticity models), detection algorithms and collision responses. Due to its high level of flexibility, Sofa is an ideal tool to quickly prototype a physical simulation. Different types of models can be combined in order to produce complex simulations, almost in real time.  

Its applications

  • Simulator for learning surgical acts in interventional electrocardiology and retinal surgery.
  • Interactive simulation of needle insertion and cryotherapy for preoperative planning.
  • Simulation of deformation and cutting of human tissues.
  • Simulation of percutaneous liver surgery with haptic feedback. 

Keywords: Digital medicine Technology platforms Inria Nancy - Grand Est centre SOFA