In Vivo Temperature Mapping during CT-Guided Thermal Ablations: Proof of Feasibility Using Spectral CT

This study aimed to perform temperature mapping during clinical ablations by leveraging the known relationship between computed tomography (CT) signal and temperature. First, the spectral CT signal was characterized as a function of temperature for soft tissue-mimicking and fat-mimicking materials across a wide range of temperatures in both frozen and heated states. Spectral CT images were acquired while fiber optic thermal sensors continuously recorded local temperatures, which were correlated with electron density changes. Substantially different material-specific thermal expansion coefficients and temperature dependencies were measured and well matched reported values. In patient images, effective atomic number images were used to segment soft tissue, fat, and bone. Electron density-temperature relationships for fat and soft tissue were used to generate temperature maps during microwave ablations and cryoablations. In vivo temperature maps correlated well with interventional radiologist expectations and demonstrated smooth transitions at fat/soft tissue interfaces.