Infrared imaging as a novel method to evaluate the efficacy of a locoregional treatment in a Vx2 liver tumor model

BACKGROUND: The rabbit Vx2 liver tumor is a fast-growing carcinoma model commonly used to study tumor behaviours under cancer treatments. The reduction of tumor viability and the degree of induced necrosis are the common criteria to evaluate the efficacy of cancer treatments. Currently, it is not easy to perform a rapid and reproducible tissue quantification by histopathological analysis. OBJECTIVE: Our objective was to use infrared-imaging combined with linear-discriminant-analysis model (LDA) to automatically quantify the necrotic effect induced by doxorubicin-eluting-implants (DEI) on a Vx2 liver tumors model. METHODS: Three rabbits were subjected to DEI treatment and compared to a control group (CTRL) of nine rabbits. Tumor bearing livers were resected, fixed in formalin and embedded in paraffin. On two consecutive sections, we performed hematoxylin–eosin–saffron (HES) staining and infrared-imaging. Infrared-images were then subjected to the LDA-model analysis. RESULTS: The LDA and HES images strongly correlated for viable and necrotic tumor tissues. For the DEI group, the model determined that the surface of viable tumor represented 0.24 ± 5% of the tumor (CTRL: 55.71 ± 17%, P< 0.0001) and the necrotic tissue 66.46 ± 20% of the tumor (CTRL: 18.45 ± 12%, P< 0.0001). CONCLUSIONS: Our results showed that infrared-imaging coupled with LDA-model analysis could be a helpful to easily and objectively assess the treatment efficacy.