To explore the effect of quantitative feedback control of the range and the frequency of the probe pressure on the reproducibility of strain ratio (SR) measurement in real-time tissue elastography (RTE).

The interactive ultrasound elastography system was achieved by integrating compression force sensors on the L74M probe of HITACHI preirus. The real-time elastographic images were acquired and displayed on a computer. Strain images were acquired by 15 operators in 3 different methods by using an ultrasound elasticity QA phantom. Method 1 was the freehand measurement by the conventional probe. Method 2 applied a compression load of 0-80 g by the integrated probe (frequency=1.5/s). Method 3 applied a compression load of 40-120 g by the integrated probe (frequency=1.5/s). In our experiment, the three methods were tested by each of 15 operators on a single cylindrical target with the stiffness of 80 kPa, diameter of 10.4 mm and depth of 3 cm. Each operator acquired 15 strain ratios for each method.

CV values had significant difference among 3 methods (F=15.853, P<0. 01) , Method 2 and Method 3 yielded lower CV values than that of Method 1 (q=4.732, 5.038, P<0. 01). CV values had no significant difference between method 2 and method 3 (q=0.625, P>0.05).

The interactive ultrasound elastography can improve the measurement reproducibility among different operators. The preload had limited effect on the results of elastography.