Preoperative 3D volume reconstruction of the posterior wall of the sphenoid sinus with Horos: A free, simple and reliable tool in endoscopic endonasal trans-sphenoidal surgery

Background: The purpose of the study was to create computer-aided design models of the sphenoid sinus with a free-source software in order to perform a preoperative planning during trans-sphenoidal endoscopic surgery (TES) and clarify the three-dimensional anatomical features of the sphenoid sinus and its surrounding structures. Methods: For each patient a 3D volume rendering of the sphenoid sinus was obtained from a thin slice head and maxilla-facial CT scan using a free-source DICOM viewer. The 3D models obtained preoperatively were examined preoperatively by six neurosurgeons in order to identify the boundaries of the sella. Results: For the main anatomical landmark, all of the observers were able to recognize the anatomical structure at a rate ranging from 80 to 98%, 28 to 60% and 25 to 58% for expert (n = 3), inexpert (n = 3) and the entire group of observers (n = 6), respectively. The analysis of the data shows that both observation groups presented a lower recognition rate of the following parameters: right and left medial and lateral optocarotid recesses and tumor prominence, however, the sellar prominence, clival recess, planum sphenoidalis, right and left ICA prominence, right and left optic prominences represent the main anatomical landmarks to be recognized during TES immediately before the opening of the sellar floor. Conclusions: The use of a preoperative 3D imaging is not in itself a novelty in the literature, however the fact that a simple tool obtained with a free-source software like Horos can represent a considerable help in surgical practice without resorting to the use of more complex software and expensive represents the real utility of this work.