The main signs of a malignant cyst transformation included size increase and wall thickening of the endometrioma, the disappearance of shading sign (i.e. an intensification of the MRI: spin-echo T2-weighted MR scans showed signal intensification, solid component at the site of papillary excrescences that were isointensive compared to outer myometrium).

      In all patients postcontrast T1-weighted FS (with fat suppression) MR scans showed a fast uptake of the contrast agent (since the first minute) by the thickened wall and solid component with the comparable intensity to that of myometrium, and a fast washout, which indicates hypervascularity.

       High b-value diffusion-weighted MRI scans (b=800) provided high signal intensity images of tumor tissue with limited diffusion at the apparent diffusion coefficient map (0,88±0,16 mm²/sec).

       The presence of solid (T1 and T2 hypointense) component in the cyst was not a reliable factor of malignancy and needed to be differentiated between malignant tumor growth, decidualization and inflammatory tissue.

Fig.1-3. A 25-year-old patient with an endometrial cyst on left ovary.

Fig.4-6. A 35-year-old patient with a large endometrial cyst with the septum.

Fig.7-11. A 41-year-old patient with an endometrioma of the right ovary. Fig.12-15. The same patient at 18-month follow-up.

Fig.16-18. A 37-year-old patient with endometrial cyst of left ovary. Fig.19-23. The same patient at 36-month follow-up.

Fig.24-25. A 29-year-old patient with an endometrial cyst of left ovary. Fig.26-28. The same patient at 12-month follow-up.

Fig.29-31. A cyst of the yellow body of ovary appears as a neoplasm with thick (up to 4 mm) wall containing a moderately heterogenous fluid on Т2-weighted MR scans.

Fig.32-34. Teratoma with the hemorrhage.

Fig.35-37. Right-sided hydrosalpinx and endometrial cyst of right ovary.

Fig.38-39. Endometrial ovarian cysts.