Ultrasound elastography of the prostate: An innovative technique for tumour-detection.

Aim: Prostate tumours are often of harder consistency than the surrounding tissue. During digital rectal examination, this fact can be used not only t o detect hypertrophy but also localized hardenings. The examination by digi tal palpation is inaccurate and, even in combination with PSA-value and a t ransrectal ultrasonic examination, the result is often not reliable. Ultras ound elastography enables us to measure and visualize the elastic propertie s of a tissue region and is a useful supplement to the examination by digit al palpation. Ultrasound elastography is able to measure and visualize the elastic properties of a tissue region, therefore it is a useful supplement to commonly used diagnostic procedures. Method: We have developed a new sys tem for elastographic prostate diagnosis which can be used during the trans rectal ultrasonic examination. During the examination a sequence of ultraso nic images is acquired while the organ is slightly compressed by the ultras ound probe. Using numerical analysis of image pairs for the acquired sequen ce we calculate the tissue strain which represents the spatial elasticity d istribution of a specific cross-section of the organ. This enables us to di stinguish hard areas in the tissue. Image artifacts resulting from lateral motion components, i.e., orthogonal to the direction of the applied force, are compensated for by a special approach. Results: We present results obta ined from a typical elastography phantom and also the first in vivo images from patients who were undergoing radical prostatectomy. Our images prove t hat ultrasound elastography has the potential to detect malignant tissue ar eas, which are inconspicuous in the B-mode image. Our findings are confirme d by the corresponding histological specimens.