ACQUISITION AND PROCESSING OF THE RADIOFREQUENCY SIGNAL IN ECHOCARDIOGRAPHY - A NEW GLOBAL APPROACH

Recently there has been an increasing interest in the use of the ''raw '' radio-frequency (RF) signal generated in echocardiography for use i n tissue-characterization to distinguish between normal and pathologic al myocardium, for automatic delineation of the endocardial border wit hout being limited by the weak contrast of the traditional video image s, and for use in contrast echography, where it could offer the possib ility to visualize perfusion using intravenous contrast injections. On e of the main problems in this kind of research is the acquisition of the signal having a high frequency and large bandwidth. We have develo ped a new global method for the acquisition of this RF signal. To digi tize the data, a video sequencer is used. In this way it becomes possi ble to sample all available data generated by the echographic equipmen t during at least 1 s. This means that all data of the complete sector scan during a complete heart-cycle can be digitized without using any data reduction technique or triggering on the electrocardiogram. The advantage of this approach is that all characteristics of the signal c an be studied, without being limited by data reduction techniques used during acquisition. This method enables us to calculate parameters su ch as ''integrated backscatter,'' or to investigate the signal more ex tensively, e.g., by using spectrum analysis. We can compare different regions of the myocardium and examine them during the heart-cycle, all within the same beat. We have also written a software package for the processing of the large amount of data resulting from the acquisition .