Tissue Pulsatility Imaging (TPI) is an ultrasonic technique developed to measure tissue displacement or strain in the brain due to blood flow over the cardiac and respiratory cycles. Such measurements can be used to facilitate the mapping of brain function as well as to monitor cerebral vasoreactivity. Significantly, because tissue scatters ultrasound to a greater extend than does blood, using ultrasound to measure tissue displacement or strain in the brain is easier to implement than using ultrasound to measure blood flow in the brain. Significantly, transcranial Doppler sonography (TCD) has been used to measure blood flow in the brain to map brain function and monitor cerebral vasoreactivity however, TCD can only acquire data through the three acoustic windows in the skull, limiting the usefulness of TCD. TPI is not so limited.
