* In minimally invasive surgery, the proper identification of the correct anatomical planes can be difficult due to a lack of tactile feedback and the inability to manually palpate the organ prior to resection. Although this can be minimized by careful preoperative planning, the information that can be obtained by images is also of limited utility. Conventional imaging, such as magnetic resonance imaging (MRI) and computed tomography (CT-scan), can provide a detailed view of 2D or 3D internal anatomical structures. However, during surgery, surgeons still have to use their subjective interpretation to translate this information into three-dimensional spatial relationships (ie the patient's actual volume). For this reason, in order to perform adequate resection and avoid injury, the surgeon must constantly infer what is the actual location of the anatomical structures and what is the position of the surgical instruments in relation thereto.
* The proposed study aims to evaluate the feasibility of surgical navigation in patients with colorectal cancer (sigmoid rectum-right-left rectum) and measure its performance in the perspective of a more specific application to rectal cancer approached laparoscopically through the abdomen and / or the anus. The study is proposed to patients with cancer because the measurement of accuracy will be done on predefined anatomical points that will be detectable in the surgical field after oncologic dissection. Benign pathologies do not require this type of extensive dissection and the application of navigation would imply additional risks for patients.
* Surgical navigation will be performed on the basis of preoperative images or intraoperative images.
