Tracking heat for cancer therapy: real-time lesion mapping

In a collaborative effort between Malta and Turkey, researchers from the University of Malta and Boğaziçi University are working on real-time monitoring technology aimed at enhancing the efficacy and precision of microwave ablation for cancer, with a focus on large-sized tumours.

The ABLAZE Project leverages Malta’s expertise in antenna engineering and the development of a dual-mode microwave ablation system, which is capable of both therapeutic and monitoring applications, alongside Turkey’s development of thermo-sensitive phantoms to optimise the microwave ablation process, potentially improving patient outcomes through enhanced real-time monitoring and feedback mechanisms.

Microwave ablation is an increasingly popular, minimally-invasive medical procedure where localised heat is delivered directly into malignant tumours to induce thermal damage. However, accurately tracking the exact boundaries of the destroyed tissue in real time has long presented a technical challenge for clinicians.

To improve this, both teams worked on a dual-antenna applicator system operating at a common clinical operating frequency of 2.45 GHz. By positioning the two minimally invasive applicators into the target tumour, the system tracks changes in the inter-antenna transmission coefficient S₂₁ as thermal energy disperses.

As tissue heats up, its dielectric properties shift, allowing the phenomenological software model to map out a precise, time-dependent two-dimensional thermal image of the treatment zone, showing exactly how the treatment is progressing.

The image shows the experimental setup, featuring ex vivo porcine liver, with both the dual-antenna array and the thermometry probe visible. The dissected liver post ablation shows the ablation zone generated through thermal damage.

Additionally, researchers worked on a novel tissue-mimicking phantoms created to validate these complex computational models. Developing physical tissue models that accurately mirror human liver organ properties is vital before clinical testing can take place. The team formulated a gel-based liver phantom using a precise mixture of water, sugar, gelatin, salt, and sodium azide. Through the combination of these materials, a physical model mimicking liver tissue was achieved, with quasi-transparent features and similar dielectric properties to liver.

To emulate cancerous tumours within the liver model, the researchers developed an innovative thermo-sensitive tumour phantom. Formulated with glycerol, acrylamide, and Bovine Serum Albumin (BSA), this spherical artificial tumour mimics the dielectric properties of in situ tumours while introducing a visual change during heating.

At room temperature ~20℃, the phantom is quasi-transparent. However, as microwave energy heats the target up to a predetermined target temperature below 80℃ that can be specifically set by the researchers, the BSA proteins denature and aggregate, turning the phantom completely opaque. This distinct optical shift enables researchers to visually confirm the shape and extent of the ablation zone alongside their temperature and transmission coefficient.

The image shows the experimental setup, featuring a temperature-sensitive tumour phantom placed within a liver phantom, with both the dual-antenna array and the thermometry probe visible. When ablative temperatures are reached, the transparent phantom becomes opaque white, visually confirming the extent of the thermal zone.

By combining Malta's antenna hardware design with Boğaziçi University's thermo-electromagnetic modelling and phantom synthesis, this partnership successfully bridges the gap between theoretical simulation and practical testing. As testing continues, this dual-antenna monitoring technique and visual phantom validation have the potential to deliver safer, more predictable, and highly localised cancer therapies for patients universally.

This work, “Project ABLAZE" is financed by Xjenza Malta and the Scientific Technology Research Council (TÜBİTAK), through the Xjenza Malta - TÜBİTAK 2024 Joint Call for R&I projects. This initiative is part of the PRIMA Programme supported by the European Union.

About the Author

Ing. Federico Cilia is an Electrical and Electronics Engineer pursuing a PhD in Physics at the University of Malta. He actively works on the ABLAZE project and contributes to the EMRG research group.

Banner photo caption (from left to right): Mehmet Emre Korkmaz, Ceren Özcan, Prof. Lourdes Farrugia, Ing. Federico Cilia, Prof. Sema Dumanli Oktar and Dr Julian Bonello.