Effects of instrument settings on radiofrequency ultrasound local estimator images: a preliminary study in a gallbladder model.

The aim of the present study was to evaluate the changes in radiofrequency ultrasound local estimator (RULES) images with different instrument settings. An Esaote Technos MPX Color Doppler Ultrasound Machine and RULES were used to capture images of a gallbladder model. The percentages of various colored areas (color filling rates) within the area of interest were calculated using different instrument gains, transducer frequencies and scan depths. Blue was predominant in the lumen of the model gallbladder, while red and green were primarily located near the inner edge of the lumen. When the depth was set at 62 mm and the gain at 105, the total color filling rates did not vary with different transducer frequencies. The blue color filling rate was greatest with a transducer frequency of 8.0 MHz, and the red and green color filling rates were greatest with a frequency of 12.5 MHz. Color variety was greatest when the transducer frequency was 12.5 MHz. When the transducer frequency was 12.5 MHz and the depth was 62 mm, the blue color filling rate was greatest with gains of 105 and 110, the red color filling rate was greatest with gains of 95 and 100 and the green color filling rate was greatest when the gain was 100. The total color filling rate was greatest at gains of 100 and 105. In conclusion, images obtained using RULES may be affected by the instrument gain and, to a certain extent, by transducer frequency.