A MODEL OF ULTRASOUND BACKSCATTER FOR THE ASSESSMENT OF MYOCARDIAL TISSUE STRUCTURE AND ARCHITECTURE

A statistical parametric model of returning echoes from myocardium is theorized in order to investigate the relationship between normal myoc ardium structure and spectral signatures with the use of ultrasonic ti ssue characterization. It is hypothesized, that in a clinical setting the normal myofiber architecture in the left ventricular wall is struc tured as a matrix of cylinder scatterers whose orientation and spatial distribution vary according to two different statistical distribution laws: 1) a Gaussian law to approximate parametric angular myofiber va riability at each site within the myocardial wall; 2) a gamma distribu tion law to describe parametric regularity in scatterer interdistance. In the model, the effect of the angle of insonification with respect to the alignment of myofibers on ultrasound backscatter was considered . The slope of the power spectral density (PSD) evaluated within the e chocardiographic transducer bandwidth has been used as a ultrasonic ti ssue characterization parameter. The model has been tested by computer simulation and in vitro measurements on myocardial pig tissue specime ns. The concordance between experimental and simulated results confirm s that the model accounts for the process underlying the echo formatio n from normal myocardium. Moreover, it provides a simple method of sim ulation which can be easily implemented and used for the assessment of pathologic alterations.