肝癌动物模型的研究进展

Comparison of mono-exponential and bi-exponential models of diffusion-weighted MRI in diagnosis of small VX2 hepatic tumors in rabbits

AIM: To investigate the value of mono-exponential model with single b-factor and bi-exponential model with extended b-factor range of diffusion-weighted imaging (DWI) in diagnosis of small VX2 hepatic tumors ( ≤ 3 cm) in rabbits.

METHODS: On the 7^th day and 14^th day after tumor implantation, 50 New Zealand white rabbits with VX2 hepatic tumors underwent DWI based on single b-factor (b values of 0 and 800 s/mm²) and multi-b-factor (b values of 0, 20, 50, 100, 200, 400, 600, 800 and 1200 s/mm²). Apparent diffusion coefficient (ADC), slow ADC, fast ADC and fraction fast ADC (f_fast) were measured in the rim of tumor (TR) and the normal region (NR) and compared between the two groups. The best thresholds of ADC, slow ADC, fast ADC and f_fast were calculated by the receiver operating characteristic curve (ROC).

RESULTS: There were significant differences between TR and NR in ADC values on days 7 and 14 (P < 0.05). The values of slow ADC of TR were superior than those of NR on both days 7 and 14. Fast ADC and f_fast of NR were higher than those of TR on the 14^th day (P < 0.05). Expect for slow ADC, no statistical difference was observed in ADC, Fast-ADC or f_fast of TR between the 7^th day and 14^th day. Slow ADC offered the highest sensitivity and specificity compared to ADC, slow-ADC, fast-ADC and f_fast for differentiating between TR and NR on both days 7 and 14.

CONCLUSION: The parameter values of mono-exponential model and bi-exponential model, especially slow-ADC, reflect perfusion of microcirculation and diffusion of water molecules, thus having value for the diagnosis of small hepatic tumors.