Thermal Ablation And Imaging Evaluation Of Rabbit VX2 Tumor

Part 1 IVIM-DWI assessment VX2 tumor efficacy of radiofrequency ablationObjective:To investigate the intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI) as a potential valuable marker to monitor the therapy responses of VX2 to radiofrequency ablation (RF Ablation).Methods:The institutional animal care and use committee approved this study. In 10 VX2 tumor-bearing rabbits, IVIM-DWI examinations were performed with a 3.0T imaging unit by using 16 b values from 0 to 800 sec/mm2. The true diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f) of tumors were compared between before and instantly after RF Ablation treatment. The differences of D, D* and f and conventional perfusion parameters (from perfusion CT and dynamic enhanced magnetic resonance imaging, DCE-MRI) in the coagulation necrosis area, residual unablated area, untreated area, and normal control had been calculated by compared t-test. The correlation between f or D* with perfusion weighted CT including blood flow, BF (milliliter per 100 mL/min), blood volume, BV (milliliter per 100 mL/min), and capillary permeability-surface area, PMB (as a fraction) or from DCE-MRI:transfer constant (Ktrans), extra-vascular extra-cellular volume fraction (Ve) and reflux constant (Kep) values had been analyzed by region-of-interest (ROI) methods to calculate Pearson’s correlation coefficients.Results:In the ablated necrosis areas, f and D* significantly decreased and D significantly increased, compared with residual unblazed areas or untreated control groups and normal control groups (P< 0.001). The IVIM-DWI derived f parameters showed significantly increased in the residual unablated tumor area. There was no significant correlations between for D* and conventional perfusion parameters.Conclusions:The IVIM-DW derived f, D, D*parameters have the potential to indicate therapy response immediately after RF Ablation treatment, while no significant correlations with classical tumor perfusion metrics were derived from DCE-MRI and perfusion-CT measurements.Part 2 Nano Fe2O3 for precision microwave ablation of renal VX2 tumorOBJECTIVE:Gelatin phantom and in vivo VX2 renal tumors model had been used to verified the usefulness of embolic material iron oxide nanoparticles-lipiodol-gelatin to improve the possibility of precise microwave ablation. MATERIALS AND METHODS:Two-room gelatin phantom model, which inner bore containing 1.0% of the nano Fe2O3 (diameter 10nm), in the distance to MWA electrode needles about 5mm away, the temperature differences had been analyzed. The CT guided renal transplant tumor model had been used to assess the usefulness of arterial infusion of nano-embolic agent through both CT and MRI, and histopathology. Altogether three rabbits, a total of six kidneys had been studied. RESULTS:In vitro experiments indicated the presence of nano Fe2O3 regional MWA temperature is significantly increased, while distinct from close range with gelatin temperature. The nano Fe2O3 prompt action can be more effective to absorb microwave energy into heat. In vivo experiments confirmed separately applications of nano Fe2O3-Lipiodol-gelatine new embolic agent, can also effectively eliminate the tumor blood supply. CT perfusion can confirm the validity of the tumor ablation, while not the MRI due to local susceptibility artifacts. CONCLSIONS:Nano Fe2O3 can improve efficiency of MWA ablation with accuracy.Part 3 Thermochemical Ablation Therapy of VX2 Tumor Using a Permeable Oil-Packed Liquid Alkali MetalObjective:Alkali metal might be a promising tool in thermochemical ablation, but needs to be further controlled to ensure its safety. The objective of this study was to explore the effectiveness of permeable oil-packed liquid alkali metal in the thermochemical ablation of tumors. Methods:Permeable oil-packed sodium-potassium (NaK) was prepared using ultrasonic mixing of different ratios of metal to oil. The thermal effect of the mixture during ablation of muscle tissue ex vivo was evaluated using the Fluke Ti400 Thermal Imager. The thermochemical effect on VX2 tumors that was induced by the NaK-oil mixture was evaluated by performing perfusion CT scans both before and after treatment of 10 VX2 rabbit model tumors. VX2 tumors were harvested from two rabbits immediately after treatment to assess their viability using trypan blue and hematoxylin and eosin (H.E.) staining. Results:The injection of the NaK-oil mixture resulted in significantly higher heat in the ablation areas. The permeable oil controlled the rate of heat released in NaK’s reaction with water in the living tissue. Perfusion CT and its parameter map confirmed that the NaK-oil mixture had curative effects on VX2 tumors. Both trypan blue and H.E. staining showed partial necrosis of the VX2 tumors. Conclusions:The NaK-oil mixture can be used successfully to ablate tumor tissue in vivo. Referring to the controlled thermal and chemical lethal injury to tumors, using a liquid alkali in ablation is potentially an effective and safe method by which to treat malignant tumors.