super(18)F-FLT PET performs better than super(18)F-FDG PET in differentiating malignant uterine corpus tumors from benign leiomyoma

• Published in: Annals of nuclear medicine Vol. 26; no. 6; pp. 478 - 484
• Main Authors: Yamane, Tomohiko, Takaoka, Aki, Kita, Masato, Imai, Yukihiro, Senda, Michio
• Format: Journal Article
• Language: English
• Published: 01.07.2012
• Subjects: Benign; Carcinoma; Cell proliferation; Malignancy; Necrosis; Nuclear medicine; Positron emission tomography; Regression analysis; Tracers; Tumors; Uterus
• ISSN: 0914-7187; 1864-6433
• DOI: 10.1007/s12149-012-0597-0

Purpose: The aim of this study is to test the hypothesis that positron emission tomography (PET) with 3'-deoxy-3'-[ super(18)F]-fluoroth ymidine ( super(18)F-FLT) can differentiate malignancy from benign leiomyoma better than PET with 2-deoxy-2-[ super(18)F]fluoro-d-glucose ( super(18)F-FDG), and to evaluate whether super(18)F-FLT and super(18)F-FDG uptake correlate with immunohistochemical index of cell proliferation. Methods: The protocol of this prospective study was approved by the institutional ethics committee, and all patients gave written informed consent. Fifteen patients (aged 26-65 years, median 44 years) with uterine corpus tumor which has the possibility of being leiomyosarcoma underwent super(18)F-FLT and super(18)F-FDG PET scans. Maximum standard uptake value (SUV sub(max)) of PET scans and Ki-67 labeling index of surgical specimens were evaluated. Mann-Whitney's U test was used for comparing uptakes between benign and malignant, and linear regression analysis was used for evaluating the correlation between Ki-67 labeling index and SUV sub(max). Results: Five cases were diagnosed as malignant (leiomyosarcoma for 3 cases, and carcinoma for 2 cases), and the others were benign leiomyoma. Sensitivity and negative predictive value of both tracers for detecting malignancy was 100 %. Specificity, positive predictive value and accuracy of super(18)F-FLT PET were higher than those of super(18)F-FDG PET. Difference in SUV sub(max) between malignant and benign was significant for super(18)F-FLT PET (P < 0.01), but not for super(18)F-FDG PET. While all the malignant cases showed positive uptake in both tracers, a case of leiomyosarcoma with huge necrosis showed relatively low uptake. Uptake of super(18)F-FLT showed better correlation with Ki-67 labeling index compared with super(18)F-FDG (R super(2) = 0.91 vs. R super(2) = 0.26). Conclusion: Negative findings on additional super(18)F-FDG or super(18)F-FLT PET may rule out the possibility of malignancy for the patients with suspected leiomyosarcoma diagnosed by conventional methods. super(18)F-FLT PET is superior to super(18)F-FDG PET in differentiating malignant from benign leiomyoma. Moreover, super(18)F-FLT uptake correlated well with the immunohistochemical index of cell proliferation.