New results with real time strain imaging

Prostate tumors can have a higher mechanical hardness than the surrounding tissue. During the digital rectal exam this can be used not only to detect the hypertrophy but also localized hardenings. The examination by digital p alpation is inaccurate and even in combination with PSA-value and a transre ctal ultrasonic examination the result is often not reliable. Ultrasound st rain imaging is able to measure and visualize the elastic properties of a t issue region and hence is an adequate supplement for commonly used diagnost ic procedures. We have developed a real time system for elastographic prostate diagnosis w hich can be used for the first time during the transrectal ultrasonic exami nation for navigation and diagnosis, During the examination a sequence of u ltrasonic images is acquired while the organ is slightly compressed by the ultrasound probe. Using a numerical analysis of image pairs of the acquired sequence the tissue strain is calculated which represents the spatial elas ticity distribution of a specific cross-section of the organ and which are able to distinguish hard areas in the tissue. We present results from several patients which show, that real time strain imaging is able to detect tumor-like areas which are inconspicuous in the b -mode image, The results correspond to the histological specimens. Furtherm ore we found that in 24 of 26 patients the tumor location and extend was co rrectly predicted (prospective study) using real time strain imaging.