Mechanical property characterization of prostate cancer using a minimally invasive motorized indenter in an Ex-vivo indentation experimen

Abstract

The aims of our study were to measure the mechanical property of prostate tissues using a minimally invasive motorized indenter and to determine whether the measurable differences in the mechanical property exist between cancer and non-cancer tissues in an $\It{ex-vivo}$ experiment. A total of 552 sites from 46 prostate specimens taken from radical prostatectomy were performed an indentation experiment with an MMI and the elastic modulus of tissue was estimated. Of 480 regions from 40 prostates specimen, 206 revealed cancer tissue on histopathological examination. The mean elastic moduli of the regions containing cancer and non-cancer tissues were 24.1 $\plusmn$ 14.5 kPa and 17.0 $\plusmn$ 9.0 kPa, respectively. In non-cancerous regions, the prostate was separated into 5 parts according to the $\It{post hoc}$ test for comparing the elasticity between groups: part 1, the lateral apex (LA); part 2, the medial apex (MA); part 3, the lateral mid (LM); part 4, the lateral base (LB); and part 5, the medial mid (MM) and medial base (MB). In regions containing cancer tissue, the prostate also could be separated into 5 parts: part 1, LA and MA; part 2, LM; part 3, LB; part 4, MB; and part 5, MM. Elasticity of Gleason score 8 was higher than other tissues. Elasticity was significantly higher in tissues with a tumor volume of over 5 ml than in the other tissues. We acquired the elasticity of prostate tissues as a quantitative and objective parameter according to the regions of prostate, presence of cancer tissue, tumor volume and the Gleason score.