A novel stereoscopic thermal endoscope for tissue damage prevention

Abstract

Multi-spectral imaging systems, namely thermal and visible spectrum imaging systems, are recently being employed successfully in multiple civilian applications, such as civil engineering , precision agriculture, and cultural heritage preservation [1], due to the more general availability of high-performing, compact sen- sors. The same success can not yet be appreciated in medical or surgical applications, with most examples of thermography in medicine being applied on the epidermis [2] or specialized applications with limited measurements [3]. Nevertheless, direct thermal tissue measurements could prove invaluable in laparoscopy and laparo-assisted robotic surgery, where bipolar electroco- agulation or ultrasonic energy are often used to achieve haemostasis to maximise a clear view of the surgical field. The temperatures exceed 45 ◦ C where disruption in the neurovascular bundles (NVB) functions was observed in vivo , with protein denaturation and subsequent cellular death occurring between 57 ◦ C and 65 ◦ C [4]. Coagulation by thermal energy can be considered responsible for the damage to the NVB that are intimately located on the lateral, posterolateral and posterior surface of the prostate during nerve-sparing robotic-assisted radical prostatec- tomy (RARP) [5]. This damage can decrease the chance of a full recovery of physiological functions after the procedure, namely the erection and urinary continence, which is estimated to be at 50% [6]. For this reason, cautery-free procedures have been evaluated to reduce the amount of induced thermal damage by using clips [7], but they introduce risk of unintentional neural bundle dissection. We present a novel endoscope prototype for minimal invasive surgery: it integrates full stereoscopic vision with 3D-mapped, direct thermal measurements to evaluate the heat propagation over the surface target tissue during bipolar coagulation. The precise mapping of the multi-spectral images would allow clinicians to quickly assess the risk of damage to sensitive tissues intra- operatively.