Differentiation Between Gaseous and Formed Embolic Materials In Vivo

Background and Purpose Doppler emboli detection is an established technique, but the nature of the underlying em-bolic material remains unclear. The intensity and spectral distribution of emboli signals could help to distinguish be-tween signals arising from formed and gaseous emboli. We undertook this study to develop and evaluate a differentiation algorithm based on the spectral characteristics of emboli signals. Subsequently the algorithm was applied to patients with mechanical prosthetic cardiac valves. Methods Emboli signals detected in patients with carotid disease, acute stroke, and atrial fibrillation were used as formed emboli data, and signals detected in patients undergo-ing cardiac catheterization studies were used as gaseous emboli data. For each embolus signal, the maximal amplitude, the sum of amplitudes, and the spectral intensity distributio