Relationship between diffusion-weighted imaging and BCL-2 expression in rabbit models of hepatic VX2 tumors after radiotherapy

The paper aims to study diffusion-weighted imaging (DWI) and Bcl-2 gene expression in hepatic VX2 tumors after three-dimensional conformal radiotherapy (3D-CRT), we successfully developed 40 rabbit models with hepatic VX2 tumors. 3D-CRT was performed on 28 rabbit hepatic VX2 tumors, which were then randomly and evenly divided into four groups. The remaining 12 controls did not receive radiotherapy. Conventional and DWI was performed at 1, 5, 10, and 15 days following radiation therapy. We measured apparent diffusion coefficients (ADCs) in both a region of interest (ROI) of the VX2 tumor tissue and normal liver tissue and then calculated the ratio between them. RT-PCR was performed to detect the expression of the anti-apoptotic gene Bcl-2. On days 5 and 10, the ADC ratios of the radiotherapy groups were 1.322±0.270 and 0.964±0.341, respectively. On days 5, 10, and 15, Bcl-2 gene expression in the radiotherapy group was 0.563±0.284, 0.421±0.242, and 0.314±0.152, respectively. For all three days, the gene expression values from the radiotherapy group were significantly lower than that in the control group (P<0.01). Statistical analysis revealed that ADC ratio and Bcl-2 gene expression were significantly negatively correlated (r=-0.493, P<0.01). Our results demonstrated that DWI sequence can reflect molecular changes at different time points for hepatic VX2 tumors following radiotherapy.