The invention provides for a medical instrument (200, 400, 500) comprising a magnetic resonance imaging system (202), a transducer (222) for mechanically vibrating at least a portion of the subject within the imaging zone. Instructions cause a processor (236) controlling the medical instrument to: control (100) the transducer to vibrate; control (102) the magnetic resonance imaging system to repeatedly acquire the magnetic resonance data (252) using a first spatially encoding pulse sequence (250); control (104) the magnetic resonance imaging system to acquire navigator data (256) using a second spatially encoding pulse sequence (254); construct (106) a set of navigator profiles (258, 804, 904, 1004, 1108, 1208, 1308) using the navigator data; determine (108) at least one parameter (260) descriptive of transducer vibrations using the set of navigator profiles; and reconstruct (110) at least one magnetic resonance rheology image (262) from the magnetic resonance data.