Anatomic Variations Of The Ostiomeatal Complex And Their Association With Chronic Rhinosinusitis: CT Evaluation.

Objective: To observe the normal anatomy and the variations of ostiomeatal complex (OMC) with thin-slice scan (1.0mm) of multi-detector row CT (MDCT) and its multi-planar reconstruction (MPR) of high-resolution; To explore the association between the anatomic variations of OMC and chronic rhinosinusitis(CRS).Materials and Methods: 193 subjects (385 sides) who underwent paranasal sinus CT scans at West China Hospital of Sichuan University from May 2006 to January 2007 were included. Ninety-nine of the patients were males and 94 were females with the average age of 40.0 years. MDCT volume scans were performed and the high-resolution MPR images were obtained. We evaluated the extent of disease and then according to the Lund-Mackay scoring system and the clinical information divided them into three groups, the normal, the CRS and the other. The normal anatomy and the variations of OMC in each subject were reviewed. Furthermore, we calculated the odds ratio (OR) and etiologic fraction (EF) of every variation resulting in CRS; compared the incidences of every variation between the normal group and the CRS one with chi-square test; and screened the risk factors of CRS by Logistic regression (backward LP).Results: HRCT and MPR could display the extent of disease, the normal anatomy and the variations of OMC more distinctly than the routine CT scan of paranasal sinus. The variation of middle turbinate is the most common with the incidence of 29.1%. The incidences of paradoxic middle turbinate and concha bullosa are 9.9% and 19.2%. The secondary is the variation of uncinate process(23.1%). The incidences of medial deviation, lateral deviation, hypertrophy and pneumatization are 14.8%, 2.6%, 3.4% and 2.3% respectively. The incidence of Onodi cell is 21.8%, large ethmoidal bulla 19.5%, Haller cell 9.9%, accessory ostium of the maxillary sinus 7.3%.The OR value of uncinate medial deviation is 2.46 ( but less than 3) and the others are less. By chi-square test ,only the difference of the incidence in uncinate medial deviation between the normal group and the CRS one was statistically significant (P=0.010),and the latter is higher than the former. By Logistic regression (backward LP), the uncinate medial deviation was screened as the risk factor inducing CRS.Conclusion: HRCT and MPR could more distinctly display the extent of disease, the normal anatomy and the variations of OMC. Their association with the routine CT scan should be refered as a kind of scan mode when undertaking paranasal sinus CT examination. The combinations of the coronal, sagittal and axis view could display the anatomy and variation of OMC more distinctly and accurately and so eliminate the artifacts.; Moreover, they provide a vivid map with bone structure for FESS, thereby contributing to the reduce of complications. Serious anatomy variations of OMC may cause CRS. However, they are not the essential pathogenesis of CRS and their roles cannot be stressed excessively. When dealing with CRS patients, the medical treatment and the surgery should be effectively combined.