Endoluminal Nd:YAG laser application in ex vivo biliary porcine tissue

Laser ablation in biliary tree: analysis of the intraductal and superficial thermal effects during the treatment

The treatment of choice for the unresectable cholangiocarcinoma is based on biliary decompression procedures. Despite stent placement is the standard of care, it is related to well-known complications. Hence, alternative techniques were proposed. Ideally, they should guarantee an adequate intraductal disobstruction, without injuring the surrounding tissues.This pre-clinical study aims to investigate the thermal effects of the laser ablation (LA) in the biliary tree, in terms of intraductal and surrounding tissue temperature achieved with different laser settings. The common bile ducts (in their upper and lower portions) of two pigs were ablated for 6 minutes with a diode laser at 3 W and 5 W. A custom-made laser applicator was used to obtain a circumferential ablation within the ducts. The intraductal temperature (T_id) was monitored by means of a fiber Bragg grating (FBG) sensor, while an infrared thermal camera monitored the T distribution in the surrounding tissues (T_sup). A maximum T difference of 65 °C and 57 °C was evidenced between the two power settings for the T_id measured in the upper and lower ducts, respectively. The mean difference between T_id and the averaged T_sup values was evaluated. At 5 W, a difference of 37±3 °C and 44±10 °C were obtained for the upper and lower ducts, respectively. At 3 W, a T difference of 2±1 °C was obtained for the upper biliary duct, while a difference of 8±1 °C was documented for the lower duct. Based on the results obtained in this preliminary study, the possibility to equip the laser probe with temperature sensor can improve the control and the safety of the procedure; this solution will guarantee the monitoring of the treatment while preserving the lumen and the surrounding structures.

Pancreatoscopy-guided laser dissection and ablation for treatment of benign and neoplastic pancreatic disorders: an initial report (with videos)

BACKGROUND AND AIMS

Per-oral pancreatoscopy (POP) permits direct evaluation of the pancreatic duct for the visualization and sampling of neoplastic lesions and treatment of pancreatic duct stones by using intraductal lithotripsy techniques. Pancreatic laser endotherapy of mucosa has been described in animal models for tumor ablation, but human experience is lacking. We describe 3 unique and challenging clinical situations that benefited from pancreatic laser dissection and ablation.

CASE DESCRIPTION

Case 1 was a 75-year-old woman with presumed divisum-associated chronic pancreatitis who had recurrent acute pancreatitis despite minor papilla sphincterotomy and therapeutic stent placement. POP showed a side-branch intraductal papillary mucinous neoplasm within the neck of the pancreas. POP-guided holmium laser ablation of neoplastic tissue was performed, followed by pancreatic stent placement every 6 months, with no further hospitalizations at 20 months of follow-up. Case 2 was a 69-year-old woman with divisum-associated chronic calcific pancreatitis and recalcitrant mid-body stenosis. Previous attempts at balloon dilation and stent placement failed to resolve the stenosis. POP-guided holmium laser dissection of the stenosis was pursued, with immediate radiographic resolution. Case 3 was a 65-year-old woman with chronic calcific pancreatitis and a large stone burden who underwent POP-guided electrohydraulic lithotripsy and partial stone extraction followed by stent placement. Unfortunately, the stent fractured during the subsequent removal attempt because the fragment was impacted in the pancreatic body. POP-guided laser dissection and lithotripsy were used to debulk dense fibrous tissue and stones surrounding the stent fragment, respectively, followed by removal.

CONCLUSIONS

Pancreatoscopy-guided laser endotherapy is a novel and potentially useful technique to manage difficult benign and neoplastic pancreatic disorders.

Laser ablation of the biliary tree: in vivo proof of concept as potential treatment of unresectable cholangiocarcinoma

OBJECTIVES

The palliative treatment of cholangiocarcinoma is based on stent placement with well-known procedure-related complications. Consequently, alternative energy-based techniques were put forward with controversial long-term results. This study aims to evaluate the safety and effectiveness of biliary tree laser ablation (LA) in terms of: (i) absence of perforation, (ii) temperature increase, (iii) induced thermal damage in in vivo models.

MATERIALS AND METHODS

The common bile duct and cystic ducts of two pigs were ablated with a diode laser (circumferential irradiation pattern) for 6 and 3 min at 7 W. Laser settings were chosen from previous ex vivo experiments. Local temperature was monitored through a fibre Bragg grating (FBG) sensor embedded into the laser delivery probe. Histopathological analysis of the ablated specimen was performed through in situ endomicroscopy, haematoxylin and eosin (H&E) and nicotinamide adenine dinucleotide (NADH) stains.

RESULTS

Temperature reached a plateau of 53 °C with consequent thermal damage on the application area, regardless of laser settings and application sites. No perforation was detected macroscopically or microscopically. At the H&E stain, wall integrity was always preserved. The NADH stain allowed to evaluate damage extension. It turned out that the ablation spreading width depended on application time and duct diameter. In situ endomicroscopy revealed a clear distinction between ablated and non-ablated areas.

CONCLUSIONS

The temperature distribution obtained through LA proved to induce a safe and effective intraductal coagulative necrosis of biliary ducts. These results represent the basis for further experiments on tumour-bearing models for the treatment of obstructive cholangiocarcinoma.