Fig. 5
From: Intermuscular hydatid cyst in the thigh musculature: a case report
A 28-year-old female with a ruptured hydatid cyst of the left vastus medialis muscle. Both T1-weighted (C) and T2-weighted (D) axial images show a hypo-intense collapsed floating membrane known as the floating membrane sign or water lily sign (blue arrow). It is pathognomonic of a hydatid cyst, representing the detached endocyst within the large cyst, consistent with a ruptured hydatid cyst