Bone window CT evaluation of the nasal cavity for the transsphenoidal approach.

Bone window CT findings sliced parallel to the transsphenoidal surgical route were evaluated preoperatively in 104 patients with pituitary lesions in order to assess their clinical significance. (1) The width and depth of the transsphenoidal operative fields were measured. The piriform aperture was 26.3 mm (SD 2.5) in maximum width, the origin of inferior nasal concha 27.0 mm (SD 2.5) and the origin of the middle nasal concha 26.8 mm (SD 3.8), respectively. The distance between the piriform aperture and the sellar floor was 61.6 mm (SD 3.6). The operative field was cylindrical in shape, approximating 26-27 mm in width and 62 mm in depth. (2) The width and length of bony nasal cavity were different by 2-3 mm in patients with and without acromegaly. (3) In re-operated patients, the location of thinned or atrophic nasal mucosa, residual bony septum and narrow sellar floor opening, which needed further bony removal were demonstrated. Bone window CT provides direct visualization of the nasal anatomy for the approach, and is useful in screening for patients with a narrow nasal cavity. It helps to determine rhinological manoeuvres for providing wide operative fields at the nasal cavity and sellar floor.