From Simulation to Surgery: Comprehensive Validation of an Optical Sensor for Monitoring Focal Laser Ablation of Solid Organ Tumors

Solid organ tumors can be treated using focal laser ablation in which a needle housing a laser fiber is inserted into a tumor and oncologic control is achieved through thermally induced tissue coagulation. The key advantage of this procedure over conventional approaches is that it has few side-effects due to its minimally invasive nature. However, the lack of an inexpensive and accurate monitoring modality hinders widespread adoption. To address this unmet need, we have developed an optical probe capable of accurately monitoring the ablation procedure in real-time, thus ensuring complete coagulation of the cancerous tissue. This is achieved by placing the probe at the desired ablation boundary and interrogating laser-tissue interaction in real-time to detect the onset and propagation of the coagulation boundary. Here, we validate this novel monitoring modality through in silico, ex vivo and in vivo studies. Monte Carlo simulation is performed to demonstrate the utility of the probe in a range of tissues including prostate, liver and brain. In all cases the virtual optical probe is capable of detecting the coagulation boundary without any tissue specific calibration. Next, an ex vivo bovine liver study is presented in which laser ablation under optical probe monitoring is shown to be capable of creating ablation zones with a radial accuracy better than 1mm. Finally, case studies from the first clinical trial of this technology are presented showing successful adoption of this technique for monitoring laser ablation of prostate cancer.