BLOOD PERFUSION MEASUREMENT WITH MULTIFREQUENCY DOPPLER ULTRASOUND

Due to its sensitivity to measurement artifacts, the ultrasonic Dopple r technique has not yet become a clinically useful tool for blood perf usion measurements. One of these measurement artifacts is caused by ul trasonic wave interference in combination with the small changes of st ructures inside the ultrasonic field. These changes are a result of va riations in blood pressure, small movements in muscles, and involuntar y movements of the transducer. The changes alter the ultrasonic interf erence pattern, causing fluctuations in the measured perfusion value. In this paper a new multifrequency technique for blood perfusion measu rement is presented. The technique is based on a multifrequency setup, with four ultrasonic frequencies simultaneously transmitted with the same transducer. It is shown that by averaging the measured values obt ained from each frequency, the sensitivity to ultrasonic wave interfer ence can be lessened. Measurement results from both in vitro and in vi vo experiments are presented.