Although it's not seen directly during the MRI scene, the plot implies that Em never removes the ring. Em would have been unable to wear the ring on her hand during the MRI (magnetic resonance imaging) test. Even if it was non-ferromagnetic (like gold), it could have still interfered with the test and medical staff would have likely removed it prior to bringing her into the room.
The Hebrew writing on the side of box in the opening scene appears upside down in relation to the lid and apparently spells out "Dibbuk" backwards. The writing on the lid apparently is backwards Hebrew for "You shall see the punishment of evil".