Session: 06-08-04: Computational Modeling in Biomedical Applications

Paper Number: 150496

150496 - Subject Specific Modeling in Cryoablation for Kidney Cancer Treatment 

In the USA, kidney cancer ranks 6th in men and 9th in women. Incidence of renal cell carcinoma has increased an average of 0.6% each year, and death rates have decreased an average of 1.6% each year from 2010 through 2022. For the year 2023, the American Cancer Society reports that of the estimated 82K newly diagnosed renal cancer cases, ~ 15K deaths are expected. Cryoablation is a less-invasive method to effectively treat cancer. Cryoablation, which relies on very low temperature (-20 °C) to produce an ice-ball in the tissue, is an important local treatment approach to kill the tumor cells while the tumor size is still small (less than 4 cm or 1.5 inches). Cryoablation is performed using hollow needles, or cryoprobes, through which cooled and thermally conductive fluids are circulated. In the cryoablation, the surgeon can monitor the ice-ball formation from CT/MRI scans. Many uncertainties involved in the cryoablation process may complicate the procedure and reduce the desired outcome, while there is a lack of adequate knowledge about this process. To complement the substantial ongoing clinical effects, new computational models leading to necessary physical insight are in urgent need for advancing the novel cryoablation treatment for kidney cancer.

A patient-specific modeling of cryoablation has been developed for kidney cancer, by considering the phase change, blood flow and metabolism. Once the needles are in place, the attached cryogenic freezing unit removes heat from the tip of the probes and by heat transfer from the surrounding tissues. The coolant flow rate is adjustable to control the cooling capability during cryoablation. We also take the surrounding liquid into consideration, which has never been discussed by previous works. In realistic condition, the kidney is surrounded by liquid or other organs in the abdominal cavity. Based on the observations in the surgery, the ice ball generated in cryoablation extends significantly beyond the kidney margin.

The model is firstly validated by comparing numerical results with reference animal experiments. With simplified kidney geometry, good agreement between numerical and clinical results shows the thermal model is validated for cryoablation simulation. For further validation, numerical modeling is utilized to simulate cryoablations in seven patients at VUMC, which covers a wide range of kidney tumors regarding sizes and locations. A novel patient specific kidney model is constructed based on the pre-surgery CT scans. Ice-ball growths during cryoablation from patient-specific modeling agree well with the in-surgery CT scan for all seven patients. From the modeling, we can find the accurate coagulative necrosis zone based on the temperature field. By comparing with the tumor to kill, we can find that cryoablation in several samples’ damages too much healthy tissue than necessary, which means cryoablation can be improved accordingly. Therefore, it is essential to develop high fidelity patient specific modeling tool for cryoablation.

Presenting Author: Zheng Li Morgan State University

Presenting Author Biography: Dr. Zheng Li is an assistant professor in the Mechatronics Engineering Department. His research interests are mainly about Multiscale and Multiphysics modeling of fluid flow and heat transfer problems in biological applications and bio-inspired designs.

Authors:

Zheng Li Morgan State University
William Winter Vanderbilt University Medical Center
Daniel Brown Vanderbilt University Medical Center
Tingying Lu Morgan State University