Colorectal cancer is the fourth-most prominent cause of cancer related fatalities across the globe. Conventional electrocautery techniques used in the resection of colon tissue cause a relatively high degree of collateral damage to the healthy tissues bordering the target sites. Ultrafast infrared lasers offer significantly improved localisation in the ablation of such biological tissues arising from a plasma-mediated ablation mechanism. This improved localisation is two-fold, with lateral confinement and precise depth control being advantageous in minimising thermal necrosis and avoiding bowel perforation respectively. Various laser scanning strategies and optical elements have been investigated, with the intent to exploit the inherent advantages offered from applying photonics to these procedures. Evaluation of the corresponding ablation characteristics was carried out using three-dimensional optical profilometry and histological analysis. If adopted in operating theatres, surgeons could benefit from more control when carrying out resection of neoplasia in the mucosal or submucosal layers of colon tissue, compared to previous electrocautery methods.
Local resection of early stage tumors in the large bowel via colonoscopy has been a widely accepted surgical modality for colon neoplasm treatment. The conventional electrocautery techniques used for the resection of neoplasia in the mucosal or submucosal layer of colon tissue has been shown to create obvious thermal necrosis to adjacent healthy tissues and lacks accuracy in resection. Ultrafast picosecond (ps) laser ablation using a wavelength of 1030 or 515 nm is a promising surgical tool to overcome the limitations seen with conventional surgical techniques. The purpose of this initial study is to analyze the depth of ablation or the extent of coagulation deployed by the laser as a function of pulse energy and fluence in an ex-vivo porcine model. Precise control of the depth of tissue removal is of paramount importance for bowel surgery where bowel perforation can lead to morbidity or mortality. Thus we investigate the regimes that are optimal for tissue resection and coagulation through plasma mediated ablation of healthy colon tissue. The ablated tissue samples were analyzed by standard histologic methods and a three dimensional optical profilometer technique. We demonstrate that ultrafast laser resection of colonic tissue can minimize the region of collateral thermal damage (<50 μm) with a controlled ablation depth. This surgical modality allows potentially easier removal of early stage lesions and has the capability to provide more control to the surgeon in comparison with a mechanical or electrocautery device.