A programmable Doppler string test object.

A prototype water filled ultrasound string test object is presented for performance checks on Doppler ultrasound systems. The string motion produces realistic and reproducible Doppler wave forms on the system by means of a programmable stepper motor. Wave forms can be generated using a computer, and programmed into the device. The test object can be used to check Doppler calculation parameters, such as pulsatility index and resistance index, as well as range gate registration and wall filter function. The test object is water filled, and the lack of attenuation did prove to be a problem on some systems. The object was tested using five different duplex and colour scanners, and found to be sufficiently reproducible for use as a field test object for Doppler ultrasound machines. The device is compact and portable, making it suitable for checks in the field for both longterm monitoring of performance and inter-machine comparisons.

The effects of angiotensin II on Doppler signals from a soft-tissue tumour.

A 10 mHz continuous-wave Doppler system has been used to detect blood flow within a sarcoma implanted in a rabbit's ear. The effects of vasoconstriction produced by intravenous angiotensin II were studied. Criteria are described that enabled differentiation of the Doppler signals from the tumour from those of the adjacent central artery. The effect of vasoconstriction upon these criteria is also described.