Monitoring of radiofrequency ablation using echo decorrelation imaging in ex vivo hepatocellular carcinoma

The feasibility of monitoring radiofrequency thermal ablation (RFA) using echo decorrelation imaging in ex vivo hepatocellular carcinoma was tested in this paper. RFA was performed using commercial RFA generator, following standard-of-care protocol, on ex vivo hepatocellular carcinoma (HCC) specimens. HCC specimens (
$N= 5$
) were obtained from patients underwent liver resection or liver transplants. RFA was guided and monitored using 128 element 8 MHz ultrasound arrays. Ultrasound images were acquired throughout the ablation process until the treatment ceased automatically due to elevation of tissue impedance or exceeding a predetermined maximum number of treatment cycles. Echo decorrelation imaging and integrated backscattered (IBS) images were computed using 20 RF beam-formed frames acquired during the ablation process. HCC specimens were sectioned along the imaging axis. Sectioned tissues were digitally scanned and segmented by an expert. Segmented tissues were co-registered with corresponding ultrasound images. Both imaging methods were assessed using receiver operating characteristics (ROC) curve. Area under the ROC (AUC) were computed to compare both methods statistically. Results showed that echo decorrelation imaging predicted RFA in ex vivo HCC tissue more accurate than IBS (AUC = 0.869, AUC = 0.775, respectively).