Medistim has developed and sold ultrasound based measurement systems for more than 30 years. The CardioMed system, launched in 1994, was the first Medistim system to utilize Transit Time Flow Measurement to accurately measure blood flow volume.

Later the VeriQ systems added Doppler measurement of blood flow velocity, and finally the VeriQ C introduced ultrasound imaging. Today, these three different ultrasound modalities are combined in the MiraQ systems to give a comprehensive analysis of blood flow and target morphology.

Transit Time Flow Measurement

The TTFM principle is based on transmitting two ultrasound beams covering the blood vessel in both the upstream and downstream direction. The blood volume flow is then derived from the difference in propagation time of the upstream and downstream beams. This measurement principle gives an accurate quantification of the real time volume flow with minimal interference with the blood vessel.

Ultrasound Imaging

Ultrasound imaging generates images by transmitting ultrasound pulses and receiving echoes from the pulses as they travel through the body. The received echoes are used to create an image of the target area. The color flow mode uses the doppler principle to detect and visualize blood flow. Pulsed wave doppler uses the same principle to measure blood flow velocity.

Doppler Velocity

The foundation of color flow imaging and doppler velocity, is the Doppler effect. The Doppler effect is the change in frequency of a sound wave caused by the motion of the sound source relative to the observer. The Doppler probe transmits an ultrasound wave burst of a known frequency and length. Objects moving towards the probe will compress the wavelength and objects moving away from the probe will increase the wavelength. The change in frequency can be detected by comparing the received signals with the transmitted signal. The changed frequency (Doppler shift) represents the velocity and direction of the reflecting object. MiraQ applies a pulsed Doppler, allowing the user to control the depth and area at which the velocities should be measured.