Value of 18F-FDG PET-CT in predicting the WHO grade of malignancy in thymic epithelial tumors

Abstract

Objective To investigate the value of18F-FDG PET-CT in predicting the simplified WHO grade of malignancy in thymic epithelial tumors. Methods The 18F-FDG PET-CT imaging of forty-five patients with pathologically proven thymic epithelial tumors was analyzed retrospectively. The patients were subdivided into a low-risk group and a high-risk group based on the simplified WHO histological classification. Spearman rank correlation analysis was used to determine the relation between parameters of PET-CT and simplified WHO histological classification. An univariate logistic regression analysis and ROC curve were performed for assessing the ability of 18F-FDG PET-CT as a predictor of the simplified WHO classification. Results There were ten patients classified into low-risk group, and thirty-five patients classified into high-risk group. Both SUVmax and SUVmax / T showed significant relationship with patients subgroup (Spearman correlation coefficients were 0.577 and 0.621, respectively, P<0.000 1). The SUVmax and SUVmax /T were found to be predictive factors that were useful to distinguish high-risk tumor from low-risk tumor(area under the ROC curve were 0.888 and 0.917, respectively, P<0.000 1). Conclusions A significant relationship is observed between 18F-FDG PET-CT findings and histological WHO classification of thymic epithelial tumors. PET-CT may be useful for predicting the grad of malignancy in thymic epithelial tumors. Key words: Thymic epithelial tumors; Histological classification; Fluorodeoxyglucose F18; Positron-emission tomography