Micro-emboli detection: An ultrasound Doppler signal processing viewpoint

Several studies have been carried out in the last twenty years on the chara cterization and detection of cerebral artery emboli, From the detection poi nt of view, the existing methods are largely based on the classical Fourier analysis of which the well known limitations provide poor accuracy. This p aper first recalls existing methods based on Fourier, Wigner-Ville and wave let approaches. It then presents new emboli detection methods based on para metric signal processing approaches. The basic idea of these parametric met hods is to compare the Doppler embolic signal to its autoregressive model, The detection principle consists in constructing a decision information whi ch contains the signature of the micro-embolus being sought. The detection is finally evaluated using receiver operating characteristic (ROC) curves. Comparison between the new methods and classical approaches is performed us ing a realistic embolic signal simulation. Furthermore, to validate our the oretical study, we tested our new algorithms using in vivo signals, This co mparison shows the significant inaccuracy of existing methods to detect mic ro-emboli.