T2 dark spot sign

T2 dark spot sign is an MRI appearance of endometriomas seen as a result of chronic hemorrhage. The sign is useful in differentiating a solitary endometrioma from a functional hemorrhagic ovarian cyst, as both might show high T1 signal with T2 shading.

The T2 dark spot, described in the sign, is seen within the cyst, often against the cyst wall, but not within the cyst wall itself (which is usually of low T2 signal due to hemosiderin-laden macrophages and fibrous component of the cyst wall).