Thermal bile duct and duodenal protection during pancreatic cryoablation.

AIM: To examine whether thermo-perfusion of the bile duct and duodenum may protect these organs during cryoablation of adjacent pancreatic tissue. STUDY DESIGN: Cryoablation of the pancreatic tissue, adjacent to the common bile duct and duodenum was performed in two groups of pigs. In the experimental group, the bile duct and duodenum were protected during the cryo-procedure by intraluminal perfusion of warm saline. In the control group, cryoablation was performed without thermo-protection. RESULTS: All three animals in the control group developed duodenal perforation and abscesses and died within a week. All the pigs in the experimental group survived and on re-operation 14 days after the first procedure were found to have normal duodenum and bile duct adjacent to the cryoablated pancreatic tissue. Histological examinations confirmed these results. CONCLUSION: The present study confirms the feasibility and efficacy of thermo-protection of the duodenum and common bile duct during cryoablation of the head of the pancreas.

Sentinel node detection in an animal study: evaluation of a new portable gamma camera.

We tested the capacity of a newly developed portable gamma camera to precisely locate sentinel nodes by injecting a radiotracer. Two sets of experiments were performed on eight pigs under general anesthesia. 99mTc-Nanocolloid and dye complex was injected in the submuscular layer of the small bowel in the first set and subcutaneously in the knee region in the second set of experiments. Image acquisition of the sentinel nodes was performed with the Camera placed at various angles. A mosaic of images was obtained encompassing the injection sites, lymphatic pathways, and sentinel lymph nodes. Three-dimensional visualizations were obtained, allowing the precise location and complete excision of these nodes. The use of the portable gamma camera allowed the rapid visualization of the lymphatic pathways leading from the injection sites to the sentinel nodes and precise location of these nodes. The Camera was also useful to verify the complete removal of the labeled target tissues.

The necrotizing effect of pulse cryocycling on liver tissue.

HYPOTHESIS: Repeated cycles of freezing improve the necrotizing effect of cryosurgery. We investigated whether multiple, very short periods of freezing and thawing (pulse cryocycling) enlarged the area of cell cryonecrosis within the iceball, compared with the standard method of cryocycling. DESIGN: Liver cryonecrosis was produced in 3 groups of rabbits by means of 2 cycles of 5-minute freezing processes, each followed by 5 minutes of spontaneous thawing. In the control group (group 1), the freezing periods were uninterrupted. In the pulse cryocycling groups, the freezing periods consisted of repeated episodes of freezing and active thawing of 15 seconds (group 2) or 30 seconds (group 3) each. The edges of all lesions were visually marked. The correlation between marking and borders of the cryolesion were examined ultrasonographically. All animals were killed on the following day, and the liver was harvested and examined histologically. SETTING: Animal experimental laboratory. RESULTS: Complete liver cell demise was observed up to the edge of the cryolesions in all 3 groups of animals. However, a thin, sharply bounded intermediate zone of incomplete tissue destruction was observed at the border of the cryolesions, which was relatively thicker in group 2. CONCLUSIONS: In our study, pulse cryocycling had no advantage compared with regular cryocycling, which obtained optimal results in normal liver tissue. However, compared with the 30-second cycles, the 15-second pulse cycling yielded poorer results.