PET/CT with 18F-FLT: Does It Improve the Therapeutic Management of Metastatic Germ Cell Tumors?

Journal of Nuclear Medicine

Gerald Reischl¹  Philip Aschoff¹  Claus D. Claussen¹  Frank Mayer¹  Roland Bares¹  Christina Pfannenberg¹  Helmut Dittmann¹  Joerg T. Hartmann¹  Claus von Weyhern¹  Lothar Kanz¹ 

关键词: germ cell tumor;    therapy monitoring;    ¹⁸F-FDG PET;    ¹⁸F-FLT PET;    residual mass;    teratoma;   

DOI  :  10.2967/jnumed.109.070425

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

Because 18F-FDG PET alone has only limited value in metastatic germ cell tumors (GCTs), we investigated the addition of 3′-deoxy-3′-18F-fluorothymidine (FLT) to 18F-FDG for early response monitoring and prediction of the histology of residual tumor masses in patients with metastatic GCT. Methods: Eleven patients with metastatic GCT were examined with both 18F-FDG PET/CT and 18F-FLT PET/CT before chemotherapy, after the first cycle of chemotherapy (early response), and 3 wk after completion of chemotherapy. In 1 patient with negative 18F-FLT PET/CT results before chemotherapy, no further 18F-FLT scanning was performed. PET images were analyzed visually and, using standardized uptake values (SUVs), semiquantitatively. The results were compared with the findings of CT and tumor marker levels and validated by histopathologic examination of resected residual masses, including Ki-67 immunostaining (7 patients), or by clinicoradiologic follow-up for at least 6 mo (4 patients). A responder was defined as a patient showing the presence of necrosis, a complete remission, or a marker-negative partial remission within a minimum progression-free interval of 6 mo. Early treatment response was judged according to the criteria of the European Organization for Research and Treatment of Cancer. Results: Before chemotherapy, reference lesions showed increased 18F-FDG uptake (mean SUV, 8.8; range, 2.9–15.0) in all patients and moderate 18F-FLT uptake (mean SUV, 3.7; range, 1.7–9.7) in 10 of 11 patients. After 1 cycle of chemotherapy, mean SUV decreased in responders and nonresponders by 64% and 60%, respectively, for 18F-FDG (P = 0.8) and by 58% and 48%, respectively, for 18F-FLT (P = 0.5). After the end of chemotherapy, mean SUV decreased in responders and nonresponders by 85% and 73%, respectively, for 18F-FDG (P = 0.1) and by 68% and 65%, respectively, for 18F-FLT (P = 0.8). The results of early and final PET were inconsistent in 6 of 11 patients for 18F-FDG and in 4 of 10 patients for 18F-FLT. Both patients with teratoma had false-negative results on both 18F-FDG and 18F-FLT. The sensitivity, specificity, positive predictive value, and negative predictive value for detection of viable tumor after 1 cycle of chemotherapy were 60%, 33%, 43%, and 50%, respectively, for 18F-FDG and 60%, 80%, 75%, and 67%, respectively, for 18F-FLT PET/CT. The respective values after the end of chemotherapy were 20%, 100%, 100%, and 60% for 18F-FDG and 0%, 100%, 0%, and 50% for 18F-FLT PET/CT. Conclusion: PET-negative residual masses after chemotherapy of metastatic GCT still require resection, since the low negative predictive value of 18F-FDG PET for viable tumor cannot be improved by application of 18F-FLT.

【 授权许可】

Unknown