In vivo elastographic investigation of ethanol-induced hepatic lesions

Ethanol-induced hepatic lesions were investigated in swine for in vivo use as a strain imaging animal model. Lesions (n = 25) were induced by injecting ethanol (doses 0.33 to 2.0 mL) directly into the surgically exposed liver at depths of 12, 15 or 25 mm. Lesions were imaged with a modified HDI 1000 scanner (Philips Medical Systems, Bothell, WA, USA). The elastograms (n = 91) characterized lesions as being areas harder than the surrounding soft hepatic tissue. Elastographic lesion sizes and the corresponding injected ethanol dose used to induce the lesions were shown to be statistically significant (r(2) = 0.22; p = 0.029) using a linear regression analysis. Additionally, lesion depth was shown to be statistically insignificant (r(2) < 0.12; p > 0.10) when regressed against elastographic lesion size. An analysis of elastographic and gross pathology lesion sizes indicated no correlation (r(2) < 0.01; p = 0.973). Subsequently, lesion types were sorted by size and regression lines were computed from quasilinear regions of the corresponding run charts. Trend lines indicate a four-to-three size relationship between the selected elastographic and pathology lesion sizes. Comparison of elastogram lesion sizes from two independent observers using a paired t-test resulted in no statistically significant difference (p = 0.14). In conclusion, ethanol-induced hepatic lesions in swine is a suitable animal model for evaluation of strain-based imaging systems, due to the ease of generation and repeatability.