Non-invasive blood flow measurements utilizing cardiac cycle

Abstract

A system for non-invasively determining the amount of blood flow by performing an autoregressive analysis of Doppler shifted acoustical signals resulting from reflected ultrasonic signals from blood cell movement within internal blood vessels. Each cardiac cycle is determined by an analysis of the patient's electrocardiogram signals,and the resulting cardiac cycles are divided into a predefined number of time segments or channels each containing Doppler shifted signals. The autoregressive analysis is then performed over each individual channel to determine reflection coefficients that model the blood flow and a residual energy level that indicates the energy not accounted for by that modeling. The reflection coefficients results result from a linear predictive code analysis, and the term 'reflection coefficients' is not used in the customary manner as defined for ultrasonic flow analysis of blood as defining a level of reflected acoustic energy. A power spectrum analysis is then performed utilizing the reflection coefficients and residual energy level for each channel. Then, the power spectra of individual channels of all of the cycles are averaged together producing a group of averaged channels representing the average blood flow through the patient's internal vessel over all of the cardiac cycles. These averaged power spectra for each combined channel are then normalized and displayed on a channel-by-channel basis utilizing different colors to represent the different power levels. The utilization of different colors greatly enhances the ability of medical personnel to make diagnostic decisions regarding the amount of blood flow.