Spectral computed tomography thermometry for thermal ablation: applicability and needle artifact reduction

Area of Science:

• Medical Imaging
• Interventional Radiology
• Oncology

Background:

• Precise monitoring of thermal ablation zones is crucial for effective liver tumor treatment.
• Computed tomography (CT) thermometry offers non-invasive temperature monitoring but is hindered by metal artifacts from ablation equipment.

Purpose of the Study:

• To evaluate spectral CT thermometry for microwave ablation monitoring.
• To compare attenuation-based and physical density-based thermometry for reproducibility, precision, and accuracy.
• To identify optimal metal artifact reduction (MAR) methods, including O-MAR and deep learning-MAR.

Main Methods:

• Dual-layer spectral CT imaging of gel phantoms during microwave ablation.
• Reconstruction of attenuation-based and physical density-based temperature maps.
• Assessment of thermometry models for reproducibility and accuracy.
• Application of MAR techniques to evaluate temperature precision in artifact-affected slices.

Main Results:

• High linearity (R-squared > 96%) between CT value and temperature.
• Physical density maps improved temperature precision by 73% in the presence of needle artifacts.
• O-MAR improved temperature precision by 49% compared to no MAR.
• Attenuation-based thermometry showed narrower Bland-Altman limits of agreement than physical density-based thermometry.

Conclusions:

• Spectral physical density-based CT thermometry at 150 keV, with O-MAR, enhances temperature precision in the presence of metal artifacts.
• This method achieves reproducible and accurate temperature measurements for liver tumor ablation monitoring.