|Planning of needle insertion into deformable tissue for percutaneous procedures is a very challenging task because of the large number of insertion points candidates and needle orientation at the insertion point. In addition, as the lesion moves from its original position during breathing or when the radiologist introduces the needle, the needle trajectory has to be permanently readjusted. This is sometimes difficult and requires real-time, high quality image feedback to measure the discrepancy between the target location and the trajectory being followed by the needle. While several methods of needle insertion have been proposed in the past, the deformation of the tissue induced by the interaction with the needle has been neglected. The aim of the research project conducted by the Institute of Image-Guided Surgery in Strasbourg (Institut Hospitalo-Universitaire, IHU). The experimental platforms available at IHU have been used to demonstrate that the interaction between liver and needle result in important deformations of the organ, mainly due to the heterogeneities of the tissue containing the pathology. The aim of the actual project is to focus on the aspects of the needle insertion related to deformation of both the tissue and the flexible needle. In this report, we present a summary of a contractual research conducted within the project Haystack. We deal with the employment of advanced numerical model of liver tissue in the process of needle insertion planning. A complex simulation scenario based on the co-rotational formulation is proposed, allowing for accurate modeling of the abdominal wall, liver, target lesion and obstacles such as bones and vascular structures. The simulation has been integrated in a pre-operative planning framework which attempts to predict iteratively the optimal entry point and the orientation of the needle, so that the target lesion be attained while minimizing the needle trajectory and avoiding important structures such as vessels.