Mean grey value is lower in endometriomas: differentiating a hypoechogenic adnexal cyst by 3-dimensional power Doppler ultrasound--a preliminary study

Background: To assess parameters of 3-dimensional power Doppler ultrasound in differentiating an endometrioma from other hypoechogenic adnexal cysts.

Methods: We collected 58 patients with classic-appearing endometriomas (homogeneous hypoechogenic adnexal cysts with round shapes) on a 2-dimensional conventional sonography. The serum level of CA-125, parameters of 3-dimensional pelvic ultrasound including the volume of the cyst, the mean grey value (MGV), and three vascular indices: vascularization index, flow index, and vascularization flow index, were measured and then, after surgical intervention, were compared between the group with histologically proven endometriomas and the group with other histological diagnoses.

Results: In the chocolate cyst group, the parity was significantly lower (0.68±0.17, p=0.012). The MGV and lesion volume of histologically proven endometriomas were significantly lower (14.78±0.7; 118.34±15.5) than those of other hypoechogenic benign adnexal cysts (17.17±0.74; 227.18±47.46), and the p values were 0.038 and 0.041, respectively. No differences in vascularization index (VI), flow index (FI), and vascularization flow index (VFI) were found between the two groups. No relationship between lesion volume and MGV in the two groups, either (p=0.127 and 0.353). We also found little correlation between CA-125 and the volume of a histologically proven endometrioma as well as between CA-125 and its MGV.

Conclusion: MGV might be useful to differentiate an endometrioma from other homogeneous hypoechogenic adnexal cysts.