Abstract:
Objective To determine the value of 18F-fluorodeoxyglucose positron emission tomography(18F-FDG PET)scans in identifying the residual retroperitoneal tumor after chemotherapy of testis germ cell tumors.
Methods Sixteen testis germ cell tumor patients with metastasis of retroperitoneal lymph nodes who were treated in our hospital from February 2014 to December 2016 were selected for the study from February 2014 to December 2016.After 4-6 cycles of chemotherapy, their CT scans showed residual masses with diameters greater than 2 cm.The retroperitoneal lymph nodes were dissected after the 18F-FDG PET exam.The post-surgery pathology results were compared with the results of the 18F-FDG PET exam.
Results Residual tumors were found in 5 of 10 patients with 18F-FDG PET positive.Residual tumor was absent in 4 of 6 patients with 18F-FDG PET negative, while residual mature teratoma tumors were found in two patients.The accuracy rate, sensitivity, specificity, positive predictive value(PPV), and negative predictive value(NPV)of the 18F-FDG PET exam were 56.25%(9/16), 71.42%(5/7), 44.44%(4/9), 50.00%(5/10), and 66.67%(4/6), respectively.
Conclusion 18F-FDG PET is highly sensitive.However, many factors influence the result of 18F-FDG PET.Mature teratoma leads to a false negative result, whereas massive tissue inflammation leads to a false positive result.Therefore, more clinical examinations should be made.