Temporal Bone Measurements; A Comparison Between Rendered Spiral CT and Surgery

BACKGROUND: Accurate radiological assessment of the anatomical features of the temporal bone is crucial to prevent damage to vital elements in this area during surgery. Knowing the approximate location of specific temporal bone related landmarks in advance is very important for planning surgery. OBJECTIVES: This study compared findings from computed tomography images with those observed directly during ear surgery. PATIENTS AND METHODS: Patients with various pathologies of the ear who needed surgery were referred to an imaging center for a spiral CT scan of the temporal bone. The following parameters were measured by a radiologist and also later recorded by the surgeon during surgery: 1) The distance between the postero-superior border of the outer ear canal and the sigmoid sinus; 2) The distance between the dome of the lateral semicircular canal and the mastoid cortex; and 3) The distance between the external surface of the incus and the mastoid cortex. RESULTS: Twenty cases were included. In the three measurements performed in this study, only the first parameter (distance between the canal and the sigmoid sinus) was significantly different between the direct measurement made during surgery and that obtained from CT scans. There was no significant difference in the measurements of the distance between the dome of the lateral semicircular canal and the bone cortex, and the distance between the external surface of the incus and the surface of the bone cortex. CONCLUSIONS: Our study shows in terms of figures that measurements of features of the temporal bone made from spiral CT scan images and those directly obtained during surgery are similar to an adequate extent.