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Image Guided and Computer Assisted Neurosurgery
Research areas

I. Minimally invasive therapies in Neurosurgery (CAS-S)

Major contributions

Our major contributions in this area are two-fold. The first aspect concerned Deep Brain Stimulation. We developed an anatomical 3T MR template dedicated to DBS. We introduced the concept of anatomo-clinical atlases for post operative assessment of Deep Brain Stimulation. We introduced a methodology for the automatic computation of the electrode trajectory respecting pre identified constraints. Both findings are some of the main aspects in the newly funded project by an ANR Blanc grant for 4 years from 2011 (ACouStiC; principal investigator: Pierre Jannin), which aims at developing an innovative strategy based on models for helping decision-making process during surgical planning and post operative assessment for increasing accuracy and precision and outcome prediction.

II. Models of Surgical Processes (SPM)

Major contributions

Our major objective within this application domain was introduce an innovative approach for understanding and formalizing the surgical practice and associated cognitive processes. We developed an original methodology for surgical modeling as well as for the identification of the different surgical aspects to be modeled. It includes a data acquisition software for pre and post operatively description of patient specific surgical process models based on the main surgical tasks. With collaborations with the ICCAS research institute from Leipzig University (Germany), we addressed different granularity levels; we validated the acquisition methodology, and studied metrics for comparing surgical process models. Discussions and works with the ICCAS group started in November 2004 were used as a basis for the creation of a new DICOM working group (WG 24: “DICOM in Surgery”). The tools we developed were used for several studies in eye surgery, brain tumor surgery, interventional neuroradiology, or spinal surgery. For instance, we demonstrated the interest of the methodology used for objectively comparing senior and junior neurosurgeons during lumbar disc herniation surgery.

III. Previous projects: Intraoperative brain deformations in neurosurgery (IGNS)

Major contributions

Our major objective within this application domain was to correct for brain deformations that occur during surgery. Neuronavigation systems make it now possible to superimpose preoperative images with the surgical field under the assumption of a rigid transformation. Nevertheless, non-rigid brain deformations, as well as brain resection, drastically limit the efficiency of such systems. The major objective here was to study and estimate brain deformations using 3D ultrasound and video information. This was performed through the integration of intraoperative 3D free-hand ultrasound and 3D intraoperative video reconstruction. The major advances in the period was to propose 1) a new 3D reconstruction framework for 3D freehand ultrasound from regular B-scans, 2) a new denoising scheme based on the adaptation of NL-Means to the Rayleigh distribution model, 3) a new rigid and non-rigid registration framework which includes a new probabilistic similarity function between MRI and Ultrasound images, and 4) a new detection, quantification and tracking of surface brain deformations from videos of the binocular microscope. We have demonstrated that millimeter deformations can be measured and corrected; with an accuracy limited to the patient to physical space registration error mainly.

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