Abstract No. 478 Shearwave elastography for characterization of tumor heterogeneity in the rabbit liver VX2 tumor

Abstract

To evaluate the diagnostic performance of shear wave elastography (SWE) imaging for differentiating normal liver from tumor and characterizing tumor heterogeneity in the rabbit liver VX2 cancer model. Nine rabbits were implanted with VX2 tumor in liver and imaged with conventional US and SWE 2-3 weeks after tumor implantation. Depending on tumor size, up to 12 ROI were placed in tumor and up to 8 ROI in normal liver. The mean, standard deviation and ratio of SWS values (m/s) and elastic modulus (SWEM, KPa) on SWE were recorded. Additionally, 2D elastic images were classified into four color patterns (red, blue, green and yellow). The area under the receiver operating characteristic (AUROC) curve analysis was performed to evaluate the diagnostic performance of SWE in differentiating tumor versus normal liver. There were statistically significant differences between tumor rim and tumor core (mean tumor rim SWEM = 32.69, SD = 18.64 KPa, mean tumor core SWEM = 13.21, SD = 2.73 KPa, p = 0.001), total tumor and liver (mean liver = 7.96, SD = 1.28 KPa, p<0.0001), tumor core and liver (p<0.001). Compared with other quantitative SWE parameters, mean values expressed in KPa had the highest AUROC value (AUROC = 0.90), with corresponding cut-off value of 17.8 KPa for differentiating tumor from liver, sensitivity of 85.1%, specificity of 96.6%, accuracy of 94.2%, PPV of 86.9%, and NPV of 96.2%. SWE with elastic modulus values can successfully differentiate tumor rim vs. tumor core vs. normal liver in the rabbit model of liver cancer.