Using the World Health Organization Classification of Thymic Epithelial Neoplasms to Describe CT Findings

Abstract

Smooth contours and a round shape are most suggestive of type A thymic epithelial tumor, whereas irregular contours are most suggestive of type C tumor. Calcification is suggestive of type B tumors. CT is of limited value, however, in differentiating type AB, B1, B2, and B3 tumors.

18F-FDG PET/CT is Useful for Pretreatment Assessment of the Histopathologic Type of Thymic Epithelial Tumors

“…If a needle biopsy is not possible or is non-diagnostic, several invasive surgical methods can be utilized for further diagnostic evaluation [1]. 18 F-FDG PET/ CT scanning may be a noninvasive method of predicting WHO histological subtypes and invasiveness of thymic epithelial tumors.…”

“…To the best of our knowledge, the application of visual uptake grading has not been reported previously in thymic epithelial tumors; thus, our results are the first to show a significant difference on 18 F-FDG PET/CT between less-and more-invasive thymomas, not merely between thymic carcinomas and thymomas, even though visual grading is more simple than measuring SUVs. Sung et al [4] reported that homogeneous 18 F-FDG uptake pattern was observed more frequently in thymic carcinomas than in high-risk or low-risk thymomas. However, in our study an increasing tendency of heterogeneous 18 F-FDG uptake pattern was seen in the order: less-invasive to more-invasive thymoma to thymic carcinoma.…”

“…Recently, several studies were reported regarding the clinical role of positron emission tomography (PET) or PET/computed tomography (CT) in the evaluation of thymic epithelial tumors. Sung et al [4] reported that 18 F-fluorodeoxyglucose ( 18 F-FDG) PET/CT was useful for differentiating among the subgroups of thymic epithelial tumors and for staging the extent of disease. Shibata et al [5] reported that maximum standardized uptake value (SUVmax) in 18 F-FDG PET and 11 Cacetate PET could be used to predict the histologic type of thymoma.…”

“…Sung et al [4] reported that 18 F-fluorodeoxyglucose ( 18 F-FDG) PET/CT was useful for differentiating among the subgroups of thymic epithelial tumors and for staging the extent of disease. Shibata et al [5] reported that maximum standardized uptake value (SUVmax) in 18 F-FDG PET and 11 Cacetate PET could be used to predict the histologic type of thymoma. However, still the studies about the usefulness of 18 F-FDG PET for the pretreatment evaluation of thymic epithelial tumor are limited.…”

“…Shibata et al [5] reported that maximum standardized uptake value (SUVmax) in 18 F-FDG PET and 11 Cacetate PET could be used to predict the histologic type of thymoma. However, still the studies about the usefulness of 18 F-FDG PET for the pretreatment evaluation of thymic epithelial tumor are limited. Therefore, we compared 18 F-FDG PET findings among the patients with various histopathologically classified thymic epithelial tumors to determine whether 18 F-FDG PET or PET/CT could be used at the pretreatment stage to distinguish between lessinvasive thymomas, more-invasive thymomas, and thymic carcinomas.…”