The Relationship Between Microwave Ablation Range and Energy in Colorectal Liver Metastasis: Based on...

To investigate the association between ablation range and energy of ultrasound (US)-guided microwave ablation (MWA) in the treatment of colorectal liver metastases (CRLM). Eighty-one patients with CRLM received MWA, which was fixed by single-electrode ablation. Conventional US and contrast-enhanced ultrasound (CEUS) were required to confirm tumor size, location, and flow perfusion before ablation, then post-ablation CEUS was employed to ascertain the ablation range. Measurements of ablation zone volume, longitudinal and orthogonal diameters, as well as their ratios to ablation energy (R_AZV/E, R_ALD/E, R_AOD/E) were conducted. The influence of CRLM characteristics on ablation efficiency was further analyzed utilizing linear regression. The R_AZV/E is 0.70 cm³/KJ, R_ALD/E is 2.47 mm/KJ, R_AOD/E is 1.70 mm/KJ. Both R_ALD/E and R_AOD/E were inversely associated with ablation energy. Through the single attenuation model, the relationship between ablation longitudinal diameter and ablation energy is finally obtained as Y (mm) = -23.27 * exp (-0.06926 * x) + 42.97. The relationship between orthogonal diameter and ablation energy is Y (mm) = -23.43 * exp (-0.05742 * x) + 34.17. MWA plateau values in longitudinal diameter and orthogonal diameter of ablation are 41.87 and 34.17 mm, respectively. And there is no significant correlation between R_AZV/E and CRLM features (such as CEUS blood supply). Theoretically, considering the safety margin of 5 mm on one side, MWA can completely ablate small CRLM whose diameter is less than 24 mm through a single fixed ablation device. The characteristics of CRLM (such as blood supply of CEUS) have little effect on ablation efficiency.