A novel elasticity assessment device, called E-finger, can distinguish prostate, bladder and rhabdosphincter tissue with a resolution of 6 mm2, according to a recent study published in PLoS ONE.

Various tools to assess the elasticity of prostatic tissue are being developed to aid in detection, diagnosis and prognosis of prostate cancer. The technologies include imaging methods, such as sonoelastography or ultrasound, and mechanical methods that aim at distinguishing benign from malignant tissue using quantitative elasticity values. However, current approaches cannot be used intraoperatively during minimally invasive radical prostatectomy (MIRP)—a procedure, in which haptic feedback might enable more precise tissue dissection and improved surgical outcomes.

In their study, Daniel Good and colleagues tested the 'micro-scale' device to determine its ability to differentiate prostatic from periprostatic tissue, such as the bladder and the rhabdosphincter. “Such knowledge is important as the objective of radical prostatectomy is to cure the patient of prostate cancer, whilst minimizing the risk of urinary incontinence, erectile dysfunction and biochemical recurrence from positive surgical margins caused by inadequate tissue dissection,” highlights Good.

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The project is based on the theory that epithelial tissues that are mainly composed of acini have viscous properties, in contrast to tissues with predominantly stromal components, which behave in an elastic manner. Owing to their distinctly different histological structures, the researchers hypothesized that the bladder and rhabdosphincter should display more elastic behaviour in comparison with the prostate, enabling distinction of these organs by direct elasticity assessment.

The goal is to create an intraoperative device to assist surgeons performing ... MIRP...

In their proof-of-principle study on two embalmed and two freshly frozen thawed cadavers, two assessors independently measured tissue elasticity with the E-finger at predefined points of a grid spanning the area of interest. Termed dynamic instrumented palpation, the E-finger created an oscillatory (frequency 1–15 Hz) indentation displacement in the tissue and recorded the resulting tissue response. Subsequently, the tissue type at each measurement point was identified by automated histochemical analysis.

Using different statistical models, the researchers demonstrated that the E-finger measurements were statistically different for the three tissue types. “Furthermore, the differences were observed in both the embalmed and freshly frozen thawed cadavers, which gives us encouragement that these differences would also be observed in live human tissue,” points out Good. “We also performed inter-rater reliability analysis, which showed good correlation.” A model using the E-finger's elasticity and detection accuracy data demonstrated that the sensitivity and specificity of this technology was 77% and 70%, respectively.

“These results encourage further development and testing in vivo,” concludes Good. “The goal is to create an intraoperative device to assist surgeons performing robotic or laparoscopic MIRP by assessing tissue quality and margins and, therefore, improve patient outcomes.”