Radiographic Reclassification of Ameloblastoma and Evaluation of the Local Effects Using CT Images

Abstract

1. Objective The objectives of this research were to perform multi-planar evaluation of ameloblastoma using computerized tomography (CT) images, reclassify the lesions in terms of locularity, and investigate the differences in the local effects according to the locularity, volume of lesion, and distribution of solid tumor nodules.

2. Materials and Methods CT and panoramic images of 144 patients that were histologically diagnosed as ameloblastoma from 2003 to 2013 were reviewed retrospectively. The lesions were classified radiographically as unilocular, pseudo-multilocular, or multilocular group according to the presence and completeness of septum on CT images. Then, each respective panoramic image was examined, and the radiographic appearances on both images were compared. The prevalence of each group was calculated. Incidence rates of local effects, such as cortical perforation and external root resorption, were calculated for each radiographic group. The volumes of lesions were also measured and then tested for correlation with locularity, cortical perforation, and external root resorption, respectively. Twenty-seven cases with contrast-enhanced CT images were studied to verify any correlation between the volume of the solid tumor nodule and the total volume of the entire lesion, locularity, cortical perforation, and external root resorption. The relationship between the location of the solid tumor nodule and cortical perforation/root resorption was also investigated.

3. Results Unilocular ameloblastoma was the most frequently encountered radiographic group in this study. Out of 144 ameloblastoma cases, sixty-three (43.7%), forty-five (31.3%), and thirty-six (25.0%) lesions were classified as unilocular, pseudo-multilocular, and multilocular ameloblastomas, respectively, under examination with CT images. Cortical perforation was found most commonly in multilocular ameloblastoma (83.3%), pseudo-multilocular ameloblastoma (62.2%), and unilocular ameloblastoma (41.3%), in decreasing order of incidence rate. External root resorption was found most commonly in unilocular ameloblastoma (72.6%), pseudo-multilocular ameloblastoma (70.5%), and multilocular ameloblastoma (68.8%), in decreasing order of incidence rate. Volumes of the lesions were also measured. The correlations between volume of lesion and locularity, cortical perforation, and root resorption were all tested to be statistically not significant (P>0.05). Different amounts of solid tumor nodules were verified within the lesions on contrast-enhanced CT images. Correlation between the volume of lesion and solid tumor nodules was tested positive and statistically significant (P<0.05). These solid nodules were found in adjacent areas of cortical perforation rather than the areas of root resorption.

4. Conclusion Different locularities, and distribution of solid nodules resulted in different effects on the surrounding structures. Therefore, examination with CT images is essential for the exact evaluation of ameloblastomas, proper treatment planning, and better prognosis of the patients.