Abstract： Objective To investigate the changes of quantitative parameters of dynamic enhanced CT in non-small cell lung cancer before and after targeted therapy,and compare them with the traditional evaluation criteria,in order to find the parameters which can be exploited for timely,objective evaluation of the effect of targeted therapy.Methods The study included 21 patients with targeted therapy who had received dynamic enhanced CT before and after treatment.Enhancement time-density curves were obtained based on the CT values of the lesion at individual time points,and the functional indices:peak height (PH),the time to peak height (Tp),the ratio of PH of the mass to aorta (M/A) and perfusion value were calculated.The effects of the treatment on these indices were evaluated and compared with the effect of the treatment on lesion diameter. Results Twenty-one patients had 33 rechecking results. There was a statistically significant agreement between lesion diameter-based treatment evaluation and perfusion-based treatment evaluation ( U =8.761,P ＜ 0.01 ). The perfusion value decreased in patients with disease regression[before treatment:(0.28 ±0.11 ) ml · min-1 · ml-1,after targeted therapy(0.18 ±0.09) ml ·min-1 · ml-1,t =- 3.2722,P =0.0042],but increased in patients with disease progression[before treatment(0.21 ±0.08) ml · min-1 · ml-1,after targeted therapy:(0.34 ±0.11 ) ml · min-1 · ml-1,t =2.6064,P =0.0403].Conclusions On dynamic enhanced CT in non-small cell lung cancer patients after targeted therapy,perfusion value changed in the same trend as the diameter of tumor.The effectiveness of targeted therapy may be evaluated by perfusion value changes.