This study aimed to determine whether magnetic resonance imaging has a role in the evaluation of the sphenoid sinus and internal carotid artery. In addition, we aimed to establish reference measurements for the minimal distance between the internal carotid arteries.

The sphenoid sinuses and neighbouring internal carotid arteries of 90 patients were evaluated using sagittal T1-weighted and axial and coronal T2-weighted magnetic resonance images.

Sphenoid sinus pneumatisation was categorised as occipitosphenoidal (0 per cent), conchal (3.3 per cent), presellar (14.4 per cent) or sellar (82.2 per cent). The internal carotid artery protruded into the sphenoid sinus in 32.8 per cent, with a septum in 9.4 per cent. The incidence of sellar-type sphenoid sinus pneumatisation was higher in patients with protrusion of the internal carotid artery into the sphenoid sinus (p < 0.001). The incidence of presellar pneumatisation was higher in patients without internal carotid artery protrusion (p < 0.001). The minimal distance between the internal carotid arteries varied between 9.04 and 24.26 mm (mean, 15.94 mm).

Magnetic resonance imaging can provide useful information about the sphenoid sinus and internal carotid artery, prior to endoscopic sphenoidotomy and trans-sphenoidal hypophysectomy.