Graham entered Thursday with a team-leading four sacks in three games. He was hurt during Pittsburgh's opening possession, went to the medical tent and then the locker room, and was ruled out for the remainder of the game.
Cleveland's depth was tested further when Mike Hall Jr. suffered a separate ankle injury in the second quarter and was carted to the locker room. ESPN's Daniel Oyefusi reported that Hall returned in the third quarter, preserving an interior option for the Browns as Graham's evaluation continued.
The MRI report narrows the uncertainty around Graham's injury. A subsequent team update is still needed to establish which games he will miss and whether Cleveland will change his roster designation.