Intraoperative fluorescence tissue characterisation using a smart forceps during robotic surgery - development and validation in large animal models

Aim: To facilitate precision radioguidance during robotic surgery a small and tethered DROP-IN gamma probe was introduced, enhancing the manoeuvrability of the detection modality [1,2,3]. In addition to radioguidance, fluorescence imaging is increasingly being used during robot-assisted surgery, in particular application with indocyanine green [ICG] (e.g., angiography and lymphatic mapping). However, next to challenges in manoeuvrability of the rigid fluorescence laparoscope, fluorescence imaging may also limit the surgical workflow: during laparoscopic surgery its overall depiction of the patient anatomy (e.g. bleedings) has proven inferior to white light imaging. Hence implementation of fluorescence imaging requires a surgeon to pause the resection, interrupting the surgical workflow. In addition, this means fluorescent tracers are not detected during the actual resection under white light. To this end, we developed and evaluated click-on fluorescence detectors that transform ‘normal’ robotic surgical instruments into fluorescence imaging devices (so-called SmartForceps), detecting the presence of fluorescence tracers in the tissues grasped during every stage of the surgical procedure.Materials and Methods: A custom fluorescence detector for ICG (fibre-based) was developed so that it could be clicked-on to ‘normal’ instruments of the surgical robot. Translational performance evaluation was assessed using: 1) phantoms; 2) during robotic surgery in pigs (n=5), evaluating angiography and lymph node localisation; and 3) on surgical specimens from clinical sentinel node procedures that made use of the hybrid tracer ICG-^99mTc-nanocolloid (n= 2; prostate cancer).Results: The resulting SmartForceps could be introduced through a standard 12 mm surgical trocar. After entrance into the abdomen, the detectors did not interfere with grasping ability or manoeuvrability of the robotic instruments. Only in fluorescent samples, as confirmed with fluorescence imaging, fluorescent count rates were detected. Porcine surgery demonstrated that the SmartForceps was able to identify blood vessels (kidney, bladder and bowel) and pelvic lymph nodes in the tissues grasped. During evaluation with human prostate cancer related sentinel lymph nodes (ex vivo), the SmartForceps was able to distinguish sentinel from non-sentinel nodes, as confirmed by fluorescence imaging and gamma probe detection. Conclusion: This study successfully introduced a click-on fluorescence-based sensing module for robotic surgical instruments, turning regular forceps into SmartForceps. This allows for fluorescence sensing during white light resections. In addition, it opens the way for biosensing applications, where the surgical instruments themselves can be used to characterise the molecular aspects of tissues.References:[1] M.N. van Oosterom et al., AJNMMI, 2016; http://www.ajnmmi.us/files/ajnmmi0016748.pdf[2] P. Meershoek et al., EJNMMI, 2019; https://doi.org/10.1007/s00259-018-4095-z[3] F.W.B. van Leeuwen et al., Clin Nucl Med, 2019; https://doi.org/10.1097/RLU.0000000000002600[4] P. Dell’Oglio et al., Eur Urol 2020; https://doi.org/10.1016/j.eururo.2020.10.031