Three-dimensional power Doppler imaging: a phantom study to quantify vessel stenosis.

This study investigated whether three-dimensional (3D) power Doppler imaging can be used to quantify arterial stenosis and its potential as an alternative to x-ray angiography. Three-dimensional power Doppler images of in vitro stenotic vessels were generated under different hemodynamic conditions with a 3D power Doppler imaging system. This system includes: a Macintosh Quadra 840AV computer used to perform 3D imaging acquisition, reconstruction and display; a computer-controlled motor-driven translation assembly used to move the transducer; and an ATL Ultramark 9 HDI ultrasound system. Three vascular- and tissue-mimicking phantoms containing three wall-less stenotic vessels with area reduction of 80%, 50% and 30% were imaged with different flow rates under both steady and pulsatile flow conditions and with different Doppler angles under steady flow condition. With the use of the blood mimic, experimental results demonstrated that power Doppler imaging is nearly independent on flow velocity and Doppler angle. It was also demonstrated that 3D power Doppler imaging can produce nonpulsatile angiographic-like 3D images of the flow field. The stenotic vessels were quantified with an overall accuracy of 8.3% of the vessel area and an overall precision of 7% of the vessel area under the conditions described in this paper. It is believed that 3D power Doppler imaging can be used to quantify arterial stenosis, and in some applications it could be an alternative to x-ray angiography.