COMPUTED AXIAL-TOMOGRAPHY OF THE PORCINE NASAL CAVITY AND A MORPHOMETRIC COMPARISON OF THE NASAL TURBINATES WITH OTHER VISUALIZATION TECHNIQUES

A non-invasive imaging modality, computed tomography (CT), was used to visualize changes in nasal turbinates of anesthetized pigs over a 12- week observation period (pigs were 14 wk of age at study week 0). Norm al, non-infected pigs were compared to pigs with mild challenge-induce d atrophic rhinitis (AR) in order to detect subtle differences in morp hology. To determine feasibility for time course studies in future exp eriments, morphometric quantitation at the level of the 2nd premolar ( turbinate area ratio or TAR) in cross-section CT images at multiple ti mepoints was done. Additionally, at study termination, the TAR determi ned from CT images, magnetic resonance imaging (MRI), and wet tissue ( WT), were compared to each other and to the standard subjective measur e, visual scoring. There were no statistically significant differences between the control and AR groups at CT imaging dates of 0, 3, 6, 9, or 12 wk (P = 0.182). However, a statistically significant decrease in TAR measurements over time (P = 0.015) was observed in both groups, w ith lower mean values observed on Weeks 3 and 6 before rebounding to b aseline values at study termination. At Week 12 (termination of the st udy), the TAR measurements derived from CT, MRI, and WT were not stati stically different from one another (P = 0.220) and the treatment grou p-by-method interaction was not significant (P = 0.800). This provided evidence of equivalency of the techniques. Mean values for normal and infected groups were not significantly different based on either TAR imaging methods (P = 0.552) or visual scores (P = 0.088). Thus, the cu rrent study demonstrated that CT was an acceptable alternative imaging modality which could be used for quantitation of turbinate changes in snouts of live pigs to provide data comparable to tissue taken at nec ropsy, Computed tomographic imaging would allow non-invasive tracking of disease or treatment responses within individual animals over time. Morphometric analysis of the TAR was equivalent between the CT, MRI, and WT specimens.