Garron Deshazer MSc, Presenter: Nothing to Disclose

Scott Collins RT, Abstract Co-Author: Nothing to Disclose

Derek Merck, Abstract Co-Author: Nothing to Disclose

Damian E. Dupuy MD, Abstract Co-Author: Research Grant, NeuWave Medical Inc Board of Directors, BSD Medical Corporation Stockholder, BSD Medical Corporation Speaker, Educational Symposia

This initial model forms the basis of ongoing work in principled thermal simulation for ablation planning. Although promising margin predictions for ex-vivo procedures were made, further experiments need to be performed to test against uncertainty and variability.  Future goals will be to test the model against other types of tissue ex-vivo, as well as incorporate tissue hetergeneity boundary conditions and heat sinks into the solution domain.      

Image-guided percutaneous ablation is an effective, inexpensive, and accessible treatment for many cancers. However, the relatively high recurrence rate in tumors over 3cm needs addressing. We hypothesize that the recurrence rate is due in part to poor margin control resulting from inaccurate, over-simplified treatment models in procedure planning. To address this shortcoming, we are developing a time-dependent thermal simulation model for percutaneous cancer ablation from first principles, and validating it against 4D experimental CT data.

The 4D simulation data was overlaid onto the 4D ex vivo experimental data. Normalized Hounsfield unit changes revealed the ablated region of interest . The simulated 60, 80, 100 -degree isothermal contour mapping, that represents a 40,60, and 80 degree change in temperature from presumptive baseline (20 degrees, room temperature) track across all time points within less than 5mm of the observed cross-sectional ablation zone.

Our model uses finite element methods to solve Penne’s Heat Equation and Maxwell’s equations for electromagnetic energy transfer over time. Given electromagnetic, power dissipation, and heat boundary conditions for the solution domain, and inputs such as antenna composition and tissue properties, time-dependent physical partial differential solutions are found. The simulation for this experiment is based on a generic antenna inside homogeneous liver tissue with a generator setting of 60 watts for 15 minutes. Validation 4D CT data sets were collected at 30-second increments during ablation procedures conducted on an ex vivo bovine liver.

Deshazer, G, Collins, S, Merck, D, Dupuy, D, A 4D Thermal Simulation Model and Validation for Percutaneous Microwave Ablation.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14003994.html