Real-time ECG-gated continuous vibration multi-shot spiral elastography acquisition: application to time-resolved cerebral stiffness measurements during arterial pulsation.

We implemented a versatile spiral MRE sequence that synchronizes the acquisition in real-time to a continuous harmonic vibration. Using multi-shot gradient echo readout and fractional motion encoding, multiple phases can be acquired in the cardiac cycle with high temporal resolution. Optionally, prospective respiratory gating and slice tracking allow for imaging moving organs like the heart or the liver in free breathing. As a first application, we measured cerebral stiffness maps in multiple phases of the cardiac cycle to detect changes induced by arterial pulsation.