Detection of Doppler Microembolic Signals Using High Order Statistics

Abstract

Robust detection of the smallest circulating cerebral microemboli is an efficient way of preventing strokes, which is second cause of mortality worldwide. Transcranial Doppler ultrasound is widely considered the most convenient system for the detection of microemboli. The most common standard detection is achieved through the Doppler energy signal and depends on an empirically set constant threshold. On the other hand, in the past few years, higher order statistics have been an extensive field of research as they represent descriptive statistics that can be used to detect signal outliers. In this study, we propose new types of microembolic detectors based on the windowed calculation of the third moment skewness and fourth moment kurtosis of the energy signal. During energy embolus-free periods the distribution of the energy is not altered and the skewness and kurtosis signals do not exhibit any peak values. In the presence of emboli, the energy distribution is distorted and the skewness and kurtosis signals exhibit peaks, corresponding to the latter emboli. Applied on real signals, the detection of microemboli through the skewness and kurtosis signals outperformed the detection through standard methods. The sensitivities and specificities reached 78% and 91% and 80% and 90% for the skewness and kurtosis detectors, respectively.

An energy detector based on negative energy fluctuations coupled with sub-band decomposition as a robust micro-embolus detection system

“…In this study, we aim to prove our detectors' high capability for micro-embolus detection and thus presents it as a serious candidate to initialize a complete methodological task for the early prevention of Cerebrovascular Accidents. This study also outperforms a recent study we have introduced, where we used high order statistics to detect micro-emboli [6]. In [5] we pointed out that the probability density function was even for Doppler signal free of embolic signature.…”

Persistent Microembolic Signals in the Cerebral Circulation on Transcranial Doppler after Intravenous Sulfur Hexafluoride Microbubble Infusion

“…The interpretation of the data from the MES detection software is challenging. Despite recent advances in automatic embolus detection, human experts are still considered the gold standard for MES detection . Assessment by one individual expert would limit the reproducibility of the result, but we addressed this by requiring consensus between three experienced observers.…”

Enhanced weak Doppler micro-embolic signal detection using energy fluctuations

“…The clinical study was approved by the ethical committee of the CHRU of Lille. The Holter Transcranial Doppler System-TCD-X (TCD-X, Atys Medical, Soucieu-en-Jarrest, France) along with the description of data collection can be found in our recently published articles [14,19].…”

“…The use of the TCD Holter version results in an increase in the number of signal artifacts. For this reason, a manual artifact rejection system was applied as in [14,19].…”