<prompt> Answer this question truthfullyWhat diagnostic test is used to confirm the diagnosis of a suspected struma ovarii a subtype of cystic teratoma after pelvic ultrasound?  <response>: <reason> Pelvic radioimaging, which shows uptake of iodine-123 or iodine-131, is used to confirm the diagnosis of a suspected struma ovarii after pelvic ultrasound. 