18F-FES and 18F-FDG PET for differential diagnosis and quantitative evaluation of mesenchymal uterine tumors: Correlation with immunohistochemical analysis

Abstract

The aim of this study was to investigate the relationship between the tumor uptake of 16α-18F-fluoro-17β-estradiol ( 18F-FES) and 18F-FDG using PET and expressions of sex hormone receptors, such as estrogen receptor (ER), as well as glucose transporter 1 (GLUT-1) and Ki-67 analyzed by the immunohistochemistry method in mesenchymal uterine tumors. Methods: Forty-seven patients with mesenchymal uterine tumors were studied with 18F-FES and 18F-FDG PET. Postoperative pathologic diagnosis revealed 33 uterine leiomyomas and 14 uterine sarcomas. Tissue samples were assayed for expression of ERα, ERβ, progesterone receptor (PR), PR-B, GLUT-1, and Ki-67 by an immunohistochemistry method. Standardized uptake values (SUVs) for 18F-FES and 18F-FDG were compared with the semiquantitative immunoreactive score (0-12) and quantitative labeling index (LI) for Ki-67 in immunohistochemistry. Results: 18F-FES uptake was significantly lower (P < 0.001) and the 18F-FDG uptake and SUV ratio of 18F-FDG to 18F-FES (18F-FDG/18F-FES ratio) (P < 0.005 and P < 0.001, respectively) were significantly higher in uterine sarcomas than in leiomyomas. Immunohistochemistry analysis showed significantly higher expressions of ERα, PR, and PR-B in uterine leiomyomas than in sarcomas. The Ki-67 LI was significantly greater in uterine sarcomas than in leiomyomas. Correlation analysis for all tumors showed positive correlations between 18F-FES SUV and immunohistochemistry scores of ERα, PR (P < 0.001), and PR-B (P < 0.005) as well as between 18F-FDG SUV and GLUT-1 and Ki-67 (P < 0.001). However, the 18F-FDG/ 18F-FES ratio showed significantly negative correlations with ERα, PR (P < 0.001), and PR-B (P < 0.005) and a positive correlation with Ki-67 LI (P < 0.001). In uterine sarcomas, ERα and 18F-FES SUV showed a positive correlation (P < 0.001) in a low SUV range, and the 18F-FDG/18F-FES ratio showed positive correlations with ERβ and GLUT-1 expression (P < 0.005). Conclusion: 18F-FES and 18F-FDG PET showed correlations between tracer uptake and expressions of sex hormone receptors, GLUT-1, and Ki-67 in mesenchymal uterine tumors. The 18F-FDG/18F-FES ratio was correlated with Ki-67, GLUT-1, and ERβ in uterine sarcoma. Functional PET imaging and PET parameters would be useful noninvasive biomarkers for the assessment of tumor hormone receptor expression, glucose metabolism, and proliferation and for differential diagnosis of uterine leiomyoma and sarcoma. COPYRIGHT © 2013 by the Society of Nuclear Medicine and Molecular Imaging, Inc.