Doppler Flow phantom Stability Assessment through STFT Technique in Medical PW Doppler: a preliminary study

Nowadays, a generally accepted standard for Doppler phantom performance assessment is lacking. In this regard, the present study is a first attempt in the definition and detection of the failures that may affect the test object flow stability, resulting in a detriment of the standard reference for Ultrasound (US) Quality Assessment (QA). As a consequence, a novel objective algorithm for the flow velocity stability assessment of flow test objects is proposed. Such image analysis algorithm is based on the application of the Short Time Fourier Transform (STFT) technique to Pulsed Wave (PW) Doppler spectrograms. Firstly, it has been tested on simulated velocity signals in which phantom failures have been added: (a) high velocity pulses deriving from the particle agglomerates of the Blood Mimicking Fluid (BMF) and (b) low frequency oscillations and velocity drifts due to the flow pump performances. Afterwards, it has been applied to real PW spectrograms. Data have been collected at three flow rates from two different flow phantom models, through a single US system equipped with a linear, a phased and a convex array probe. Despite this novel STFT application has revealed itself as a promising tool in the detection of Doppler phantom failures, further tests should be carried out for the optimization of both the algorithm and the test protocol.