Characterizing the compression-dependent viscoelastic properties of human hepatic pathologies using dynamic compression testing.

Recent advances in elastography have provided several imaging modalities capable of quantifying the elasticity of tissue, an intrinsic tissue property. This information is useful for determining tumour margins and may also be useful for diagnosing specific tumour types. In this study, we used dynamic compression testing to quantify the viscoelastic properties of 16 human hepatic primary and secondary malignancies and their corresponding background tissue obtained following surgical resection. Two additional backgrounds were also tested. An analysis of the background tissue showed that F4-graded fibrotic liver tissue was significantly stiffer than F0-graded tissue, with a modulus contrast of 4:1. Steatotic liver tissue was slightly stiffer than normal liver tissue, but not significantly so. The tumour-to-background storage modulus contrast of hepatocellular carcinomas, a primary tumour, was approximately 1:1, and the contrast decreased with increasing fibrosis grade of the background tissue. Ramp testing showed that the background stiffness increased faster than the malignant tissue. Conversely, secondary tumours were typically much stiffer than the surrounding background, with a tumour-to-background contrast of 10:1 for colon metastases and 10:1 for cholangiocarcinomas. Ramp testing showed that colon metastases stiffened faster than their corresponding backgrounds. These data have provided insights into the mechanical properties of specific tumour types, which may prove beneficial as the use of quantitative stiffness imaging increases.