Use of enhanced T2 star-weighted angiography (ESWAN) and R2* values to distinguish ovarian cysts due to endometriosis from other causes

Purpose To evaluate the feasibility of enhanced T2 star-weighted angiography (ESWAN) in differentiating endometrial from non-endometrial cysts. Methods Forty-nine patients with 60 histopathologically proven ovarian cystic lesions underwent pelvic MRI including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), liver acquisition with volume acceleration, and ESWAN. Ovarian cystic lesions were divided into endometrial cysts (group 1; n = 28), pyosalpinx and hydrosalpinx (group 2; n = 13), and ovarian cystic and cystic-solid tumors (group 3; n = 19). R2* (effective transverse relaxation rate) values were measured and pairwise comparison of the R2* values among the three groups was made using Kruskal–Wallis test. Receiver operating characteristic curves were used to calculate cutoff values and performance of R2* values for distinguishing among groups. T1WI signal intensity and R2* value were also compared using area under curve values. Results R2* values for group 1 were statistically higher than groups 2 and 3 (15.37, 1.40, and 1.79 Hz, respectively; P < 0.001). The cutoff value for R2* was 7.43 Hz with a sensitivity, specificity, PPV, NPV, and accuracy of 96.43, 87.50, 87.10, 96.55, and 91.67%, respectively. There was no significant difference between the R2* value and T1WI in diagnosing endometrial cysts. Conclusions The R2* value provides an effective way to discriminate endometrial cysts from other ovarian cystic lesions.