Evaluation of neovascularization with spectral computed tomography in a rabbit VX2 liver model: a comparison with real-time contrast-enhanced ultrasound and molecular biological findings

Objective: To validate the feasibility of using the parameters of spectral CT and CT perfusion and the dynamic features of real-time contrast-enhanced ultrasound (CEUS) to evaluate the vascularization of VX2 hepatic tumours. Methods: Spectral CT imaging, CT perfusion and CEUS analysis were performed on rabbits implanted with VX2 hepatic tumours, 7 and 14 days after implantation. The perfusion parameters of CT, normalized iodine concentration (NIC) and dynamic features of CEUS were measured in the rim of the tumour (TR) and the normal liver region. The expression of vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2) was also determined. Results: Increased perfusion parameters of CT were found in the TR. In addition, the NIC was elevated in TR during the arterial phase, and the peak intensity of the CEUS of the TR was reached significantly earlier than that on normal liver region. At 14 days, the perfusion parameters of CT (blood volume, permeability surface and hepatic arterial fraction) offered higher accuracy and stability in differentiating the TR from the normal liver region. Furthermore, CEUS was more accurate in diagnosing tumours < 1.0 cm in diameter. In addition, VEGF and FGF2 expression was higher in the TR and were positively correlated with CT and CEUS parameters, except mean transit time, rise time, washout time and peak time. Conclusion: Use of spectral CT with perfusion techniques, iodine-based material-decomposition analysis and dynamic CEUS changes may reflect the angiogenesis and haemodynamic information of hepatic tumours. Advances in knowledge: It is feasible to assess vascularization in hepatic cancer using CT or CEUS.