Preoperative MR imaging for differentiation of immature from mature ovarian teratomas

Objective: The purpose of this study was to differentiate immature from mature ovarian teratomas, using magnetic resonance (MR) imaging and to evaluate the MR imaging appearance of immature teratomas. Methods: The patients with pathologic diagnosis of ovarian teratomas between January 1995 and December 2005 were restrospectively reviewed for clinicopathologic characteristics. Results: Of the 787 patients studied, 773 (98.2%) patients were mature cystic teratomas and 14 (1.8%) patients were immature teratomas. Ten patients with immature teratoma (71.4%) were diagnosed preoperatively and 4 patients (28.6%) were diagnosed postoperatively. Preoperative MRI was performed in 4of 14 patients surgically proved immature teratomas. At MR imaging, the immature teratomas characteristically have a large, irregular solid component containing coarse calcifications and numerous variable-sized cysts. Small punctuate foci of fat help diagnosing these tumors. Conclusion: Preoperative MR imaging are relatively specific in the detection of immature teratomas. This suggests that preoperative MR imaging is helpful in differentiating immature from mature ovarian teratomas.