In vivo ultrasound thermal ablation control using echo decorrelation imaging in rabbit liver and VX2 tumor

Abstract

The utility of echo decorrelation imaging feedback for real-time control of in vivo ultrasound thermal ablation was assessed in rabbit liver with VX2 tumor. High-intensity focused ultrasound (HIFU) and unfocused (bulk) ablation were performed using 5 MHz linear image-ablate arrays. Treatments comprised up to nine lower-power sonications, followed by up to nine higher-power sonications, ceasing when the average cumulative echo decorrelation within a control region of interest exceeded a predefined threshold (− 2.3, log10-scaled echo decorrelation per millisecond, corresponding to 90% specificity for tumor ablation prediction in previous in vivo experiments). This threshold was exceeded in all cases for both HIFU (N = 12) and bulk (N = 8) ablation. Controlled HIFU trials achieved a significantly higher average ablation rate compared to comparable ablation trials without image-based control, reported previously. Both controlled HIFU and bulk ablation trials required significantly less treatment time than these previous uncontrolled trials. Prediction of local liver and VX2 tumor ablation using echo decorrelation was tested using receiver operator characteristic curve analysis, showing prediction capability statistically equivalent to uncontrolled trials. Compared to uncontrolled trials, controlled trials resulted in smaller thermal ablation regions and higher contrast between echo decorrelation in treated vs. untreated regions. These results indicate that control using echo decorrelation imaging may reduce treatment duration and increase treatment reliability for in vivo thermal ablation.

A Review of Quantitative Ultrasound-Based Approaches to Thermometry and Ablation Zone Identification Over the Past Decade

“…The results showed that AUROC values of ablated area predicted by echo decorrelation imaging were >.8 in liver tissue and >.7 in tumor tissue. Abbass et al [84][85][86] investigated the strategy of real-time control and feedback of HIFU and bulk ultrasound ablation of bovine liver in vitro and rabbit liver with VX2 tumor in vivo using echo decorrelation imaging. The closed-loop control condition of ablation was that the minimum-decorrelation (Min dec ) or average-decorrelation (Ave dec ) in the selected region of interest (ROI) exceeded control thresholds.…”

Phosphotungstate Acid Doped Polyanilines Nanorods for in situ NIR-II Photothermal Therapy of Orthotopic Hepatocellular Carcinoma in Rabbit

“…14 To transmit enough laser energy to the deep-buried tumors through malignant tissues deeper than 10 cm, operative exposure is a common option, which has the problem of large damage. 15 Optical fibers, which are small (few hundred micrometers in diameter), flexible, nontoxic, and chemically inert, have already proven to be valuable for in vivo clinical applications such as endoscopic procedures, illumination light guides, and laser power transmission for surgical applications. 16 Hence, we hypothesize that optical fibers could be inserted into the deep-buried tumors to transmit NIR-II laser energy to deeped buried tumors for in situ NIR-II photothermal therapy.…”