Sono-Elasticity: Medical Elasticity Images Derived from Ultrasound Signals in Mechanically Vibrated Targets

Abstract

Cancers of the prostate have traditionally been detected by digital palpation which identifies increased stiffness (modulus of elasticity, hardness) of the abnormal tissue. Gray-scale ultrasound is insensitive to stiffness as an imaging parameter and often fails to reveal the extent or existence of a prostate cancer. Recent developments in technology and understanding have improved the diagnostic efficacy of transrectal ultrasound for detection of early prostate cancer, but even when coupled with digital rectal examination, a significant percentage of existing carcinomas may not be recognized. This statement is based on the lower detection rates for transrectal ultrasound and digital rectal examination in screening populations (0.1-4%) as compared to autopsy series prevalance rates of approximately 30%. Recent reports suggest that early cancers of the prostate may be characterized as hypoechoic areas in the peripheral zone of the prostate (1). Others suggest that the more advanced lesions have varied appearances ranging from hypo to hyperechoic with some even showing combinations of both (2,3). Our transrectal ultrasound experience from patients with palpable cancers (which include moderately to advanced disease), suggests a varied non-specific gray-scale appearance as well, despite the uniform impression that they are all firm on digital palpation.