The devices, systems, and methods described herein facilitate determining whether a patient moved during an imaging procedure causing potentially significant inaccuracies. In some, embodiments, the devices, systems and methods may also or alternatively facilitate correcting the information obtained from the MRI or other imaging procedure in view of the patients movement or other inaccuracy creating event. There is provide a reference device (100,700,800,900) including a rod (110,710,810,1010) having a known length, a first end (112), and a second end (224) and one or more opaque markers (120,130) connected to each of the ends.
