A 4-AFC Study Comparing Ultrasound Machines Using a Greyscale Phantom

Abstract

Two ultrasound machines, one high-end and one ordinary, were compared in terms of their ability to reproduce low-contrast objects using the same probe. Images containing 4 mm objects of four different contrasts were collected from a greyscale phantom at 35-42 mm depth. Six observers participated in a 4-alternative forced choice study based on 120 images. At this certain depth and object size the proportion of correct responses was higher (statistically significant) for the high-end machine at three of four contrast levels, indicating the possibility to discriminate between ultrasound machines using a limited number of images of a greyscale phantom. However, the number of images and number of observers needed are larger than usually used for constancy control.