The Fundamental Study Of Percutaneous Laser Coagulation For Liver Tissue

1. Objective(1) Assess to the influence of the different optical parameters and the fiber types on the coagulated volumes in laser-coagulated liver tissues that are fresh killed pig liver and animal liver with or without b100d supply.(2) Fundamental Experiment:The purpose of the study isTo explore the possible ways of enlarging the limited LCV of PLCT,for an effective therapy for hepatic tumor.To evaluate the influence of hepatic b100d flow on the magnitude of the coagulation.To study the thermal distributive laws of LITT which is essential to therapeutic strategy.The correlation was revealed among the laser-coagulated power(LCP),time(LCT),LCV,and LC shape(LCS).2. Materials and methodsLaser coagulation was carried out using a neodymiu-yttrium garnet (Nd:YAG) laser (Laser institute of Shanghai) on fresh domestic pig lives in vitro and New Zealand rabbits in vivo (with or without b100d supply).(2) A special diffusing tip for percutaneous treatment were developed.(3) Experimenting in vitro,we try to describe:The ascending curves of temperature along with the time of the points in the maxium short axis plane.The curves of temperature of the above-mentioned points at certain moments.The temperature characters at the edge of the coagulated area and next to it,the transition area in vitro and in vivo.The influence of the LCP on the curves above.The influence of hepatic flow with complete occlusion (arterial and portal) versus physiological flow on the magnitude of the coagulation in different LCP and LCT was investigated.Real-time and color Doppler imaging of the treated area has been investigated.3. ResultsThe investigation predicted a fourfold to fivefold increase in the area of coagulation in liver without b100d flow than that with b100d flow(P<0.001).The temperature at the LC area and the transition area is permanently 50-52.5 C,45C-48C respectively,no matter whether power or time in vitro or in vivo.In the thermal field,on the maxium short axis plane,the temperature (y) of a point and its distance(x) from the core agree to the equation:X =-2py+b. Low laser power and long exposure times contribute to higher temperature and larger LCV. But carbonization have a negative influence on heat transport.The cells in coagulated area including the transiton area are necrosed completely,and the neighboring tissue also severely damaged.4. Conclusion(1) The vascular inflow occlusion in animal models confirm that significantly larger lesions were obtained when the hepatic b100d flow was interrupted.(2) A special diffusing tip for percutaneous treatment were developed allowing the emitted laser light to be distributed eqully throughout the surrounding tissue.(3) Low or medial LCP and long LCT contribute to the temperature of points in thermal field amply increased to a high plateau,meanwhile,contribute to LCV expanding.(4)As complete necrosis also occurs in the transition area,it must be taken into account in the therapeutic planning.