Learning Objectives: To understand surgical anatomy of the temporal bone using a medical imaging processing system.

Introduction: Although canal wall down mastoidectomy still plays an important role in treatment of cholesteatoma, the chance of performing this procedure appears to be decreasing by appropriate intervention for ear diseases that develop cholestatoma. The decreasing chance to master this technique should be compensated by other methods. As one of the alternatives we introduce a simulation and education method of ear surgery using a medical image processing system.

Methods: Sagittal 2 and 3 dimensional reconstructive images (DRI) of the temporal bone CT scan are made for this purpose using a three-dimensional image analysis system volume analyzer (SYNAPSE VINCENT, Fuji Film Co, Tokyo, Japan).

Results: Sagittal 3DRIs introduced here show, in the order from lateral to medial, the antrum cavity, the prominence of the lateral semicircular canal, the incus body, the malleus head, the bridge being formed, the second genu of the facial nerve canal, the bridge resected at the level of the malleus neck, the mastoid segment of the facial nerve canal, the completely resected bridge, the lateral semicircular canal, and the completely opened facial recess. These images also show that the lateral wall of the attic has anterior-posterior and superior-inferior slants. 2DRIs parallel to the lateral wall of the attic show that the resection of the bridge parallel to the lateral wall is safe without risk of injury to the ossicles, the facial nerve, and the inner ear. However, sagittal 2 and 3DRIs should be evaluated for each patient due to individual differences in the temporal bone anatomy and bone structural changes affected by the disease.

Discussion and Conclusions: Since ear surgery usually progresses from lateral to medial, sagittal 2 and 3DRIs from lateral to medial simulate ear surgery including canal wall down mastoidectomy. Medical imaging processing systems are a useful and inexpensive tool to understand complicated anatomy about ear surgery, especially for novice surgeons.