Evaluation of laser-induced plasma ablation focusing on the difference in pulse duration.

A pulsed laser cause vaporization of tissue by plasma if a laser can provide high-density energy within a very short pulse duration. Such phenomena are called laser-induced plasma ablation. The influence of the laser-induced plasma ablation for tissue is unclear because the ablation mechanism is differing regardless of two lasers provide almost the same power density. The two kinds of lasers' vaporization mechanism (Nanosecond laser output could cause an optical breakdown in the air depending on power density and pulse duration of the laser and Femtosecond laser output could cause a breakdown only on solids surface since pulse irradiation time is shorter than energy transfer time) are evaluated by using thermal damage and destruction of tissue. The experimental results show that nanosecond laser caused vaporization without thermal damage and destruction at the tissue approximant 300 µm away from the ablation area. The pulsed laser which has high power density and longer pulse duration than energy transfer time is suitable for plasma ablation not depending on thermal process.

Intraductal oncocytic papillary neoplasm of the pancreas with strong accumulation on FDG-PET.

This paper reports a case of resected intraductal oncocytic papillary neoplasm (IOPN) of the pancreas. A 69-year-old woman was admitted with right hypochondriac pain. Ultrasonography, contrast-enhanced computed tomography and magnetic resonance imaging showed a cystic lesion, 10cm in diameter, in the head of the pancreas. The lesion contained a number of mural nodules 1cm in diameter with thick walls, which demonstrated hypervascularity. The main pancreatic duct was slightly dilated, 7mm in diameter. 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) showed very strong uptake in the thick wall and mural nodules of the tumor. Substomach-preserving pancreatoduodenectomy (SSPPD) was performed. The patient is presently alive and well without any evidence of recurrent disease 18 months after the operation. IOPN has the potential to develop into invasive carcinoma, and therefore, should be completely resected whenever possible.