Cool Image... This image series shows only simple anatomic structures. In my advanced lectures that are given to sinus surgeons, complicated anatomic principles can be explored. Here you can see the image-guided surgery system. This system imitates one used during endoscopic procedures. Wherever the pointer points, the corresponding CAT scan cuts are displayed. The CAT scan data can also be incorporated directly into the scene as shown. The scan at the level of the sphenoid is seen. The right sphenoid is partially transparent. An anatomic location called the hiatus semilunaris superior is demonstrated. 1999 Peter Casano, M.D.