Real-time Elastography for the Diagnosis of Prostate Cancer: Evaluation of Elastographic Moving Images

Elastography is a technique for detecting the stiffness of tissues. We applied elastography for the diagnosis of prostate cancer and evaluated the usefulness of elastography for prostate biopsy. The subjects of this study were 311 patients who underwent elastography during prostate needle biopsy at Hitachi General Hospital. Strain images obtained during compression of the prostate tissue were displayed on a monitor and recorded on the computer. The elastographic moving images (EMI) were evaluated retrospectively. The evaluable images and biopsy results were compared in terms of the feasibility and accuracy. The median patient age was 67 years (range 50-85 years), the median serum level of prostate-specific antigen was 8.4 ng/ml (range 0.3-82.5 ng/ml) and the median prostate volume was 42.6 ml (range 12-150 ml). Among the 311 patients, prostate cancer was detected in 95 patients (30%) by biopsy. The diagnostic sensitivity was 37.9% for digital rectal examination (DRE) and 59.0% for transrectal ultrasonography (TRUS), whereas it was 72.6% for elastography and 89.5% for the combination of TRUS and elastography. Elastography-positive EMIs with negative biopsies were eventually determined to be due to benign prostatic hyperplasia. Elastography has a significantly higher sensitivity for the detection of prostate cancer than the conventionally used examinations including DRE and TRUS. It is a useful real-time diagnostic method because it is not invasive, and simultaneous evaluation is possible while performing TRUS.