Fig. 1

Functional hemorrhagic ovarian cyst in a 28-year-old woman with dysmenorrhea and acute pelvic pain at the time of MRI, and no medical history. a Axial T1-W fat-suppressed MR image shows a T1-hyperintense left hemorrhagic ovarian cyst (arrow). b Axial T2-W MR image shows a heterogeneous cyst (arrow) with upper hypointense lace-like reticular areas (arrowhead) and lower fluid-fluid level (star) with T2 shading. c Axial T1-W contrast-enhanced subtracted MR image shows homogeneous hyperintense rim wall enhancement (arrow). d Axial diffusion-weighted MR image shows an equivalent hyperintense “DWI-ring sign” (arrowheads) compared to c