Three-dimensional imaging of the petrous bone for the middle fossa approach to the internal acoustic meatus: an experimental study.

The goal of this study was to highlight the feasibility of creating three-dimensional (3D) pictures of the petrous bone from a routine CT examination which can be used for a middle fossa approach to the internal acoustic meatus, in order to secure this operation. The surgical aim is to reach the roof of the internal acoustic meatus directly without injuring the adjacent functional structures of the petrous bone. Two heads of embalmed cadavers were scanned every millimeter with a slice thickness of 1 mm centered on the petrous bones. The horizontal reference was the Frankfurt line and the frontal and sagittal planes were perpendicular to this line. This method is similar to routine examinations for surgical patients. The pictures were first loaded on an optical disk, then into a computer (Silicon Graphics System). Amira software was used to create 3D pictures. The anatomy of the temporal bone could easily be identified, notably the surgical landmarks of the middle fossa approach. Three-dimensional computer-assisted imaging can reveal the anatomy of the petrous bone in a realistic view. The main anatomic structures for a middle fossa approach can be recognized easily. This realistic view may be very useful for surgeons, and 3D images deserve to be developed further.