In this study, microwave thermal ablation is numerically evaluated in the context of a treatment for Conn's Syndrome. This condition is caused by a benign shallow tumor in the cortex of adrenal gland. The modeling and design of microwave applicator to deliver thermal ablation to the adrenal gland requires accurate tissue characterization. Measuring the dielectric properties of the constituent tissues in the adrenal gland, that is cortex and medulla, enables more accurate numerical modeling for electromagnetic and thermal simulations. This study presents an anatomically and dielectrically realistic numerical model of the adrenal gland, and investigates the feasibility of applying controlled heating to small targets in the adrenal cortex. In addition, the use of dielectric contrast between the fat and the cortex of the adrenal gland to focus the thermal energy in the gland has also been studied. Being conscious of limitations of numerical simulation of complex multi‐physics problems like the microwave ablative treatment, calculated results provide a preliminary description of the electromagnetic and thermal phenomena involved.

Microwave thermal ablation has been thoroughly investigated in the last decades. However, new challenges for this technology are nowadays represented by specific applications. The present work investigates a promising ablative solution for the treatment of functional adenomas in the adrenal gland. A numerical study conducted to build and test an optimized internally cooled triaxial antenna will be presented. The antenna has been designed to minimize its transversal dimension merging radiating and cooling elements. The proposed antenna has been then built in our laboratories and experimentally tested on Ex vivo biological tissues. Numerical and experimental results will be reported and discussed.

Esophageal varices are a significant complication of portal hypertension. Endoscopic variceal ligation (EVL) is one of the clinical standards for treating these varices and preventing their hemorrhage. Limitations of EVL include the risk of stricture formation and postband ulcer bleeding due to the damage caused to the esophageal mucosa, as well as the need for multiple endoscopic treatment sessions to eradicate the varices. The goal of this study is to develop a device and evaluate the technical feasibility of microwave ablation to seal esophageal varices, while preventing thermal damage to the surface mucosal tissue. A microwave applicator with a directional radiation pattern was developed for endoscopic ablation of esophageal varices. Electromagnetic and bioheat transfer computational models were employed to optimize the design of the microwave applicator and evaluate energy delivery strategies for this application. Experiments in ex vivo and in vivo tissue were employed to verify simulation results. Simulations predicted enhanced heating performance of the antenna using an angled monopole radiating element. Further, simulations indicate that while the endoscopic cap attenuated electric fields in tissue, it also enhanced surface cooling of tissue, increasing the likelihood of preserving mucosal tissue. Experiments in ex vivo tissue indicated the feasibility of sealing veins with 77 W microwave power delivered for 30 s. In vivo experiments demonstrated the ability to seal veins, while preserving surface tissue. This study demonstrated the technical feasibility of microwave thermal ablation for treating esophageal varices using a 2.45 GHz water-cooled directional microwave applicator.

Some of the authors of this publication are also working on these related projects: Non-invasive measurement View project Urinary Bladder Monitoring using Electrical Impedance View project