Arthur Wijsmuller, MD1, Luis Romagnolo, MD2, Bernard Dallemagne, MD1, Armando Melani, MD2, Céline Giraudeau, PhD3, Jacques Marescaux, MD, FACS, Hon, FRCS, Hon, FJSES, Hon, FASA1. 1Research Institute against Digestive Cancer (IRCAD), Strasbourg, France, 2IRCAD América Latina, Barretos, Brazil, 3IHU Strasbourg, Institute of Image-Guided Surgery, Strasbourg, France
Introduction: Transanal TME for rectal cancers is increasingly adopted by surgeons, but is recognized as a procedure that requires expertise since recognition of anatomical planes during this approach can be challenging. Stereotactic navigation is a validated intraoperative guidance tool for neurosurgery, orthopedics and spine surgery and might be valuable for rectal surgery, since rectum is relatively fixed extraperitoneally in the pelvis and may not be affected by pneumoperitoneum and respiratory movements. The aims of this preliminary study on human cadavers were to evaluate the rectal anatomical changes induced by pneumoperitoneum and lithotomy position and the value of stereotactic navigation.
Methods and Procedures: This preliminary study was conducted on two human corpses, on which the fiducials of a stereotactic navigation system (StealthStation™, Medtronic) were placed. Pre-operative radiological images, CT scan, MRI and Artis Zeego (Siemens), acquired in 2 different positions (supine and lithomomy), with and without pneumoperitoneum, were analyzed to assess the anatomical changes induced on the rectum and the levator ani muscle and variations in position of the registration fiducials. Then, these sets of images were used successively in the navigation system to evaluate the best registration method by measuring the registration error provided automatically by the system and the anatomical matching of defined landmarks (origin of the inferior mesenteric artery, aorto-iliac bifurcation, urethra and levator ani muscle) between the CT-MRI images processed by the navigation system and the anatomy provided by laparoscopy in abdominal and transanal approach.
Results: Comparison of CT and MRI images in supine and lithotomy positions, with and without penumoperitoneum showed minimal changes (±2mm) in the position of the rectum and levator ani muscle. Position of the fiducials was greatly impacted by the position of the corpse and pneumoperitoneum rendering the registration process inaccurate (registration error: >4mm). Best registration (<2mm) and anatomical landmarks matching (<1mm) were obtained with an intraoperative scanning of the corpse in lithotomy position and pneumoperitoneum with the Artis Zeego.
Conclusions: This preliminary study demonstrated that changing the position of the patient for transanal surgery and a laparoscopic pneumoperitoneum induce very little changes in the anatomy of the intra-pelvic organs, as compared to a radiological image acquired in supine position. Stereotactic navigation for transanal surgery was shown to be feasible, although the perfect set-up for optimal registration needs further studies. Stereotactic navigation may potentially be applied toward pelvic organs, thereby opening the gateway for a broader use by the general surgeon.
Presented at the SAGES 2017 Annual Meeting in Houston, TX.
Abstract ID: 79003
Program Number: S137
Presentation Session: Colorectal 2
Presentation Type: Podium