MRI system, in particular a method and system for generating a cardiac trigger signal

A system for providing a trigger signal for controlling the operation of a scanner, comprising:

• a laser speckle vibrometry system for non-contact vibration sensing, comprising a laser for delivering laser light, a defocused optical system, and an optical detector for detecting reflected laser light, wherein the defocused optical system is for defocusing the laser light at the distance of the surface of a body of a patient to be scanned;
• and
• a patient coil arrangement for mounting against the body of the patient;
• wherein the patient coil arrangement comprises at least one window enabling the passage of the laser light to the body of the patient;
• a mounting arrangement for mounting the laser such that the delivered laser light passes through the window of the patient coil arrangement;
• and
• a controller which is adapted to process the detected reflected laser light to detect the cardiac cycle and to generate a cardiac trigger signal for the control of the scanner.