The Role of OsiriX Based Virtual Endoscopy in Planning Endoscopic Transsphenoidal Surgery for Pituitary Adenoma

Virtual endoscopy (VE) is the navigation of a 3D model reconstructed from radiological image data. The aim of this paper is to evaluate the role and accuracy of the virtual endoscopy realized using commercially available software, OsiriX, as a method of planning of surgical interventions.

The computed tomographies of 22 patients with pituitary adenomas proposed for endoscopic approach were reconstructed using OsiriX. VE was performed prior to surgery to assess the surgical corridor and particular anatomy. We evaluated the following landmarks: inferior and middle turbinate, sphenoid ostia (SO), choanal arch (Ch), sphenoethmoidal recess (SER), sphenoid septa, sella turcica, carotid prominences and opticocarotid recesses (OCR). The intraoperative endoscopic images were reviewed and compared with the virtual images.

The virtual images had a good resemblance with the actual surgical images. All the structures from the nasal cavity were identified and had a perfect matching except the SO which was identified in 8 cases in VE vs. 12 intraoperative. All the structures from the sphenoid sinus were identified with perfect matching except the ipsilateral carotid prominence (14 in VE vs. 10 intraoperative) and the contralateral carotid prominence (16 in VE vs. 18 intraoperative). The VE could not show the state of the sellar floor and did not offer any information about the sellar content.

VE realized in OsiriX represents an affordable alternative to the specially designed systems, offering reliable data and good quality images that are useful for the preoperative planning, but some limitations are present such as inability to obtain additional information in cases where the sphenoid sinus is fully occupied by tumor or not aerated, inability to clearly differentiate between structures at the level of the sella, and impossibility to simulate working instruments.