Indication of Doppler sampling on the video image of a linear scanner without modification of commercial equipment

There is often a need for combining an ultrasound real-time scanner of one make with an ultrasound Doppler meter of a different make. This usually requires complicated and expensive adjustments of both apparatuses. This study describes how it is possible to identify the Doppler beam and locate the sample volume by adding a line to the video signal. The line ends at a point corresponding to the preselected depth of the pulsed Doppler showing the middle of the sample volume. The Doppler probe is mounted in a holder fixed to the scanner head. The holder allows rotation of the Doppler probe to form angles (35-90 degrees) with the scanner head surface. The sample volume indication corresponded well with actual sampling when tested on an in vitro flow rig and on different peripheral vessels. Modifications of neither scanner nor Doppler meter was necessary.