Noninvasive detecting the focal cerebral ischemia

This study shows that the time-frequency distribution of the Somatosensory Evoked Potential (SEP) is very sensitive to cerebral ischemia. SD rats are used for animal experiments and a model for SD rat focal ischemic cerebral injury is presented. Then, based on the Discrete Gabor Spectrogram (DGS), SEP signals from the animal experiment are analyzed. Center of power (COP) and weight center of power (WCOP) is defined. The study proves that the time-frequency feature of SEP signals in the ischemic region is obviously different from the normal region, and can be clearly distinguished by analyzing the SEP signals in the time-frequency domain. The injury extent can also be detected by analyzing the time-frequency features. The authors' study may result in a quantitative method to detect focal ischemic cerebral injury in the earlier phases.