Intraoperative model based identification of tissue properties using a multimodal and multiscale elastographic measurement approach

During minimally invasive surgery the visual (3 dimensional) and mechanical (haptic) feedback is restricted or even nonexisting, which imposes a serious loss of important information for decision making. Information about the mechanical properties of the biological tissue helps the surgeon to localize tissue abnormalities (benign vs. malign tissue). The work described here is directed towards assisting the surgeon during minimally invasive surgery, which in particular relates to the segmentation and navigation based on the recovery of mechanical properties. Besides the development of noninvasive elastographic measurement techniques, a reliable constitutive FE model of the organ (describing its mechanical properties) is generated resulting in a further improvement of the segmentation and localization process. At first silicon phantoms, with and without foreign bodies have been generated for the purpose of testing the transfer of information (delivery and processing of data). The stress-strain curve was recorded and embedded in the FE Model (Arruda-Boyce). Two dimensional (2D) displacement maps have experimentally been obtained from the phantom, which were in good agreement with the FE simulation.