On the correlation between the texture of contrast agent ultrasonic image and the intracardiac pressure

Base on the application of box-counting fractal model to the textrue analysis of ultrasonic image after intravenous injection of Levovist acoustics contrast agent in a dog, a method to calculate the fractal dimension(D) and assistant characteristic(C(L)) of the ultrasonic images of left ventricle is presented. It is found that the D and C(L) changed regularly in the continued cardiac cycles, that is, the maximum value of D appears during diastasis, and the minimum value appears during end-systole; as the ventricular systole begins, D changes from maximum to smallness, and as the diastole begins, D changes from smallness to maximum; the maximum value of C(L) appears around end-systole, and the minimum value appears around diastasis; from the start of left ventricular systole to end-systole, C(l) shows a tendency to change from smallness to maximum, and from the start of diastole to diastasis, it shows a tendency to change from maximum to smallness. The changes of D and C(L) are very similar to the changes of left ventricular pressure. It is thus evident that there is correlation between the fractal texture characteristics of the contrast agent ultrasonic images and changes of intracardiac pressure. The results demonstrate that it is possible to measure the intracardiac pressure noninvasively.