A clinical study of echo decorrelation imaging during percutaneous thermal ablation of hepatocellular carcinoma

Minimally invasive thermal ablation of liver tumors, including microwave and RF ablation, would benefit from improved intraprocedural monitoring to assess treatment progress. Echo decorrelation imaging has been proposed to quantify rapid echo signal changes caused by tissue heating. Previous studies have shown that echo decorrelation is a better predictor of ablation effects than changes in echogenicity. Here, the feasibility of monitoring percutaneous thermal ablation of hepatocellular carcinoma (HCC) using echo decorrelation imaging was tested in a clinical study. Consenting subjects were recruited from patients scheduled for standard-of-care HCC ablation. Subjects underwent radiofrequency ablation guided by B-mode ultrasound (US) with imaging frequency 2.2 MHz. Throughout each ablation procedure, groups of 20 sequential beamformed RF frames were acquired at 30 s intervals. Acquired beamformed frames were used to compute B-mode US, echo decorrelation, and integrated backscattered (IBS) images. B-mode US images were coregistered with follow-up triphasic CT images. Receiver operating characteristic (ROC) curves were calculated to assess prediction of local ablation by thresholded echo decorrelation and IBS maps. Area under ROC curves showed that echo decorrelation imaging predicted local percutaneous RFA significantly better than IBS imaging in patients with HCC. Although further study is needed, these results suggest that echo decorrelation imaging is an effective approach for percutaneous thermal ablation monitoring in patients with HCC.