Specifications, constraints and Proofs

Permanents staff

• 2 professors : Jean-François Dufourd and Pascal Schreck
• 4 assistant professors : Caroline Essert, Nicolas Magaud, Pascal Mathis, Julien Narboux

Other participants

• 1 Associate researcher: Gabriel BRAUN (MC UFR LSHA, 09/2009-)
• 1 Maître de conférence en délégation CNRS: Laurent FUCHS (MC Poitiers, 09/2010-09/2011)
• 3 Post-doctoral: Claire BAEGERT (ATER, 01/2010-08/2010), Christophe BRUN (ATER, 01/2011-08/2011), Simon THIERRY (ATER, 10/2010-08/2011)
• 1 PhD students: Rémi IMBACH (Ministère, 10/2010-)
• 3 Former PhD students: Claire BAEGERT (Région Alsace-IRCAD, 10/2005-12/2009), Christophe BRUN (Ministère, 12/2007-12/2010), Simon THIERRY (Ministère, 10/2006-09/2010).

Formalisation and planning of surgical interventions

In these works, we propose an original approach to assist automatically the planning of a position of a surgical tool. Our method allows for elaborating an optimal strategy of intervention, specific to the patient and to the type of intervention, thanks to an automatic computation which is based on the expertise of the field and the preoperative data.

To this end, we put into play some approaches coming from declarative modeling and geometric constraint solving, to compute automatically optimal trajectories for rigid and straight surgical tools. The comutation of the trajectory is performed in several steps. First, the expertise of the surgeon on a given type of intervention is transcribed under the form of mathematical equations (equalities, cost functions). Then those equations are formalized into geometric constraints, written under the form of terms combining geometric and arithmetic operators and the data coming from the medical images (MRI, CT). A first computation solves the so-called "strict" geometric constraints (boolean constraints) to provide the space of possible solutions. Finally a second computation solves the so-called "soft" geometric constraints called (numerical constraints) thanks to a numerical optimization, to provide the optimal solution.

We tested our approaches on 2 types of interventions : the ablation of hepatic tumors by radiofrequency (hyperthermia) in collaboration with Pr. Gangi from the service of radiology of the Hôpital Civil of Strasbourg, and the implantation of electrodes of deep brain stimulation in collaboration with Dr. Haegelen from the service of neurosurgery of Renn's University hospital Pontchaillou.

The PhD thesis of Claire Baegert dealt with this topic Bae09. Various publications were published regarding radiofrequency EBS09, BES07, BES07, BES07a, BES07b and deep brain stimulation EHJ10. These works also leaded to a collaboration with DKFZ Heidelberg on the acceleration of occlusions solving thanks to GPU ESF10, SES11.

These works gave rise to the ANR project ACouStiC, which started in january 2011 for 4 years, and in which IGG team is a partner. This research topic is part of the IHU of Strasbourg.

Perspectives

Regarding surgical interventions planning, in the framework of ACouStiC project among others, we are beginning an extension of the field of possible solutions, by studying curved, multiple and volumetric trajectories. This will allow us to extend the posible applications to deformable surgical tools, within deformable tissues, or multiple tools used simultaneously (for instance cryoablation of hepatic tumors), or even access volumes such as craniotomy in the context of exeresis of cerebral lesions. We will also work on constrained surgical navigation within the solution space, in order to restrain the interactive modification of the proposed trajectory into a space of possible/reasonable solutions. To this end, the link will be done with "Visualization and interactions" axis of our team, in particular the haptic interfaces topic.