The Value of Measuring Eustachian Tube Aeration on Temporal Bone CT in Patients with Chronic Otitis Media

OBJECTIVES To evaluate that the cross-sectional area of the air space in the Eustachian tube (ET) on computed tomography (CT) images could be useful for predicting the postoperative aeration of the middle ear. METHODS The patient group consisted of 80 patients (80 ears) with chronic otitis media and who underwent middle ear surgery from 2006-2007 and who were followed up for more than 1 yr. The control group consisted of 100 ears of 50 individuals with normal tympanic membranes and who underwent CT for other causes (such as tinnitus or hearing loss). The largest cross-sectional areas of the aerated ET were measured on the coronal images of the temporal bone CT by a single otologist using the computer-based "Region of Interest" picture archiving and communications system. The patient group was divided into two subgroups, 1) those with good postoperative aeration and 2) those with poor postoperative aeration. The largest cross-sectional areas of the aerated ETs were compared between the patients and the controls, and between the patients with good aeration and the patients with poor aeration. RESULTS The mean cross-sectional areas significantly differed between the patient group and the control group, and between the good and poor aeration subgroups (P<0.05 each). The mean area of the poor aeration subgroup was smaller than that of the control group (P<0.05), but the mean area of the good aeration subgroup did not significantly differ from that of the controls. CONCLUSION The cross-sectional area of the aerated ET, as measured on the preoperative coronal images of temporal bone CT scans, may be useful for predicting the postoperative condition of the tympanic cavity.