A magnetic resonance imaging system includes a bore, a table configured to support a patient being imaged and movable to move the patient in and out of the bore, a motion sensor, a controller configured to detect patient motion based on changes in an RF signal from the motion sensor. The motion sensor includes a self-resonant spiral (SRS) coil excited by a drive signal to radiate a magnetic field having a predefined resonant frequency and a driver-receiver coupled to the SRS coil and configured to generate the drive signal to excite the SRS coil and to receive the RF signal from the SRS coil. The motion sensor is located such that a portion of the patient is within the magnetic field while the patient is being imaged in the bore.