AMPLITUDE DOPPLER US - SLOW BLOOD-FLOW DETECTION TESTED WITH A FLOW PHANTOM

PURPOSE: To evaluate the in vitro sensitivity for the detection of slo w blood flow in tiny tubes with an amplitude Doppler ultrasound (US) t echnique at different angles and pulse repetition frequencies. MATERIA LS AND METHODS: Human blood treated with heparin was pumped through si licone tubes (flow phantoms made by the author) with lumina of 3.00 mm , 0.30 mm, and 0.05 mm. Slow flow was imaged by using amplitude and co lor Doppler US techniques with two US devices at different pulse repet ition frequencies and angles and in different sound propagation media. RESULTS: Under ideal conditions, the lowest detectable velocity was 0 .04-0.06 cm/sec in the 3.00-mm tube. Detection was about three to four times less sensitive in the 0.30-mm and 0.05-mm tubes. Amplitude Dopp ler US sensitivity is only slightly dependent on the angle of incidenc e and propagation medium. CONCLUSION: The fractional volume flow deter mined the sensitivity of the amplitude Doppler technique for detecting low flow. Amplitude Doppler US is nearly angle independent; thus, it is superior to color Doppler US. Amplitude Doppler US is three to four times more sensitive when tubes have very tiny lumina and when probes of a lower frequency are used.