Background: The present study investigates the usefulness of 18F-FDG-PET/CT (PET/CT) in distinguishing between benign and malignant ovarian teratomas.
Methods: This study includes 4 mature teratomas (MTs) with malignant transformation, 8 immature teratomas (ITs), and 16 MTs that were diagnosed after surgical resection. Preoperative tumor marker values, MRI findings, PET/CT SUVmax values, and other clinical parameters were retrospectively compared with those of 14 patients who had MTs.
Results: The median CA125 was significantly higher for ITs than for MTs (P = 0.04). The median AFP was significantly higher for ITs than for MTs (P = 0.0034). The median SUVmax values for MTs with malignant transformation, ITs, and MTs were 18.3 (5.3-23.3), 6.0 (3.6-22.6), and 1.1 (1.0-15.5), respectively. SUVmax was significantly higher in MTs with malignant transformation and ITs than in MTs (P = 0.004, P = 0.0007). With a cut-off SUVmax of 3.6 to distinguish between benign and malignant MTs, sensitivity was 100 %, specificity was 81 %, positive predictive value was 80 %, negative predictive value was 100 %, and diagnostic accuracy was 89 % (AUC 0.94). However, one patient with an MT had a high SUVmax corresponding to values in the central nervous system (CNS).
Conclusions: 18F-FDG-PET/CT has a high diagnostic accuracy in distinguishing between benign and malignant ovarian teratomas. Thus, PET/CT may be useful in cases where the diagnosis is unclear on MRI and other clinical findings. However, some MTs with abundant CNS tissue may have a high SUVmax. Therefore, the diagnosis of a benign or malignant lesion should be made carefully in conjunction with other clinical findings.
Keywords: FDG-PET/CT; Immature teratoma; Malignant transformation; SUVmax; Teratoma.