ELASTOGRAPHIC IMAGING OF LOW-CONTRAST ELASTIC-MODULUS DISTRIBUTIONS IN TISSUE

Elastography is a new ultrasonic imaging technique that produces image s of the strain distribution in compliant tissues, This strain distrib ution is derived from ultrasonically estimated longitudinal internal m otion induced by an external compression of the tissue, The displayed two-dimensional (2-D) images are called elastograms, In this paper, it is demonstrated that, when signal-to-noise ratio-enhancing techniques are used, elastography is capable of imaging low-contrast elastic mod ulus tissue structures with high contrast-to-noise ratios, This is dem onstrated using both computer simulations and data obtained from 3 day s postmortem ovine kidneys in vitro, The elastograms of such organs su ggest that the modulus slowly decays from the renal cortex (RC) to the interior of the renal sinus (RS), Such modulus variation is corrobora ted by independent measurements of the Young's moduli, It is found tha t the RC is approximately twice as hard as the interior of the RS, We invoke our previous results on elastographic contrast-transfer efficie ncy to demonstrate that, at low contrast, the elastogram may be interp reted as a quantitative image of the relative Young's modulus distribu tion. (C) 1998 World Federation for Ultrasound in Medicine & Biology.