Room: AAPM ePoster Library
Purpose: Thermochemical ablation (TCA) is a novel treatment under development for hepatocellular carcinoma. In TCA, an acid and base are delivered simultaneously via a catheter localized within the tumor. The reagents react at the catheter tip, producing salt, water and heat products, inducing tumor ablation. TCA treatment monitoring is challenging with typical reagents (i.e. NaOH and HCl) not imageable. This can be overcome with CsOH as a base with theranostic properties.
Methods: Seven CsOH standards (0.195-125 mM) were made by serial dilution and placed into an elliptical phantom (Multi-Energy CT Phantom, Kyoto Kagaku). Images were acquired on a split-filter DECT system (Definition Edge, Siemens Healthineers) at 120 kVp, Au/Sn filter, and CTDIvol 13.6 mGy. The limit of detection was determined according to published methods.
Ablation simulations were performed in ex-vivo tissue. Image acquisition is described above. Five CsOH standards (6.0-50 mM) were placed within the scan field of view to develop a calibration plot. 0.5 mL injections of 6.0-50 mM CsOH were performed. 40 keV monoenergetic images were generated on Syngo Via. Line profiles were obtained with ImageJ (NIH, Bethesda, MD) through the ablation zone.
Results: The limit of detection for CsOH is 7.8 mM in phantom. HU value correlated strongly with CsOH concentration (R²=0.999). The peak HU values were 375 HU and 175 HU for ablation simulation in tissue at 50 and 25 mM CsOH, respectively. Decreasing concentration from the injection site is illustrated in the line profile across a linear distance of approximately 10-12 mm. Concentrations as low as 25mM were visually identified and confirmed by line profile in tissue.
Conclusion: This work demonstrates CsOH as a viable theranostic agent for image-guided TCA interventions. Accurate spatial distribution of concentration is achieved with DECT for monitoring and assuring complete tumor ablation.