Very different performance of the power Doppler modalities of several ultrasound machines ascertained by a microvessel flow phantom

Table 4 Settings for detection of lowest flow velocity in the 150 μm vessel

Machine	Pulse repetition frequency/velocity range	Wall filter	Doppler frequency
A	1.3 cm/second	Level 1	8 MHz
B	125 Hz	Level 1	10 MHz
C	150 Hz	15 Hz	R1^a
D^b	200 Hz	Level 1	10 MHz
E^b	1,000 Hz	Low	12.5 MHz

^aActual frequency not displayed on this machine. ^bNo flow detected in this vessel.

ISSN: 1478-6362