A feasibility study of prostate needle biopsy supported by freehand elasticity imaging

Prostate tumor-like areas are often inconspicuous in conventional transrectal ultrasonography (TRUS). Therefore, a needle must be injected into the prostate gland in many places to obtain a biopsy. As an alternative, we propose using a tissue elasticity imaging method for needle biopsy support, based on the principle that cancerous prostate tissue becomes hard. A tissue elasticity image should reduce the number of times a needle must be injected, and decrease the probability of small cancers being overlooked. We developed the tissue elasticity imaging system for prostate glands. As a demonstration, we measured some prostate glands suspected of being cancerous. Although cancer detection is difficult using a conventional B-mode image, the strain image clearly indicates the cancerous area to be hard. A comparison of strain images with needle biopsy results revealed a 94 % agreement (15 out of 16) with histological examination in detection of cancer. We therefore concluded that the tissue elasticity imaging method is useful as a prostate needle biopsy support technology.