Micro-embolic signatures detection through GARCH parameters
Résumé
Detection of micro-emboli is of great clinical importance to prevent cerebro-vascular events. Standard detection techniques implemented in the most commonly used systems are generally based on the comparison between a decision information (energy) and a threshold. The value of this threshold can be set just above the statistically highest detected energy of a blood Doppler signal. This choice of threshold consequently prevents all detection of micro-emboli events whose energy might be lower than the systolic energy. In this study three detectors were tested and compared: i) a standard energy detector, ii) a detector based on AR parameters and iii) a detector based on GARCH parameters. From in vivo signals and for a detection rate set to 100%, the false alarm rates were of 33%, 5% and 3% for the standard energy detector, for the detector based on a AR(2) model and for the proposed detector based on the GARCH(1,1) model, respectively. This study demonstrates that GARCH technique detects micro-emboli which did not identified by classical methods. Large micro-emboli are all detected, but small micro-emboli are only detected with parametric techniques. The new detector opens up new prospects to detect small emboli, despite the need for further studies to incorporate technique "on line".
Domaines
Acoustique [physics.class-ph]
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