Optimisation of tumor ablation by monitoring tissue temperature via CT

PhD ceremony: Mr. G.D. Pandeya, 12.45 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Optimisation of tumor ablation by monitoring tissue temperature via CT

Promotor(s): prof. M. Oudkerk

Faculty: Medical Sciences

Non-invasive thermometry using imaging techniques such as magnetic resonance imaging (MRI), ultrasound (US) and computed tomography (CT), allows optimising thermal ablation by monitoring real-time temperature distribution in tumors and adjacent vital organs. Although early studies primarily assessed the thermal sensitivity of CT in biological samples, technical limitations hampered further investigation of CT thermometry. Therefore, the potential of current CT was explored to assess the thermal sensitivity and implemention for CT thermometry.

Thermal sensitivity of CT was evaluated during radiofrequency ablation and laser ablation while synchronously measuring the temperature using thermal probes. A hypodense area was observed close to the heating source caused by a change in CT numbers in CT image due to increase in temperatures. The results showed an inverse linear dependency between temperatures and area-averaged CT numbers in all experiments. The thermal sensitivity ranging from -0.35HU/°C to -0.65HU/°C in ex-vivo models and -0.03HU/°C to -0.43HU/°C in in-vivo models was determined. In addition, the thermal sensitivity was translated into a color coded temperature map showing the temperature distribution during ablation. From this study it is concluded that non-invasive CT thermometry is feasible. The criteria for non-invasive thermometry proposed by Frich et al. [2006] were accomplished, except the temperature resolution. Further in-vivo studies are required to improve the concept of non-invasive CT thermometry and implementation in clinical practice for the treatment of tumors with real-time temperature monitoring.