Abstract: Objective To explore the application of ultrasound contrast and micro blood flow imaging in differential diagnosis of atypical primary liver cancer （PLC） and focal nodular hyperplasia （FNH）. Methods 35 patients with atypical PLC and 40 with FNH were selected in our hospital between January 2014 and December 2015. All the patients underwent ultrasound contrast and micro blood flow imaging,and the features of PLC and FNH were analyzed and compared. Results The ultrasound contrast showed that the arrive time of contrast agent [（4.1±0.7） s] and the time to peak [（37.8±11.4） s] in the PLC group were significantly longer than those [（2.5±1.0） s and （24.2±9.5） s] in the FNH group,while the peak strength[（23.1±5.7） dB] was obviously lower than [（30.6±4.3） dB] in the FNH group（P<0.05）;As showed by the ultrasonogram of liver tumors in enhancement,there were 19 foci being with patchy enhancement and 16 with ring-enhancement in the PLC group,while in the FNH group,there were 29 foci being with annulare enhancement and 11 with eccentric enhancement in arterial phase,40 foci showing hyper-enhancement in portal phase,16 being with hyper-enhancement,22 with same enhancement and 3 with low-enhancement in delayed phase（P<0.05）;the results of micro blood flow imaging showed that the maximum artery blood flow velocity （Vmax） was[（64.7±3.3） v·cm^-1·s^-1] in patients with PLC, obviously lower than[（77.8±5.1） v·cm^-1·s^-1] in the FNH group,while the resistant index （RI） was [（0.70±0.05）],much higher than [（0.53±0.03）] in the FNH group （P<0.05）;There were 3 foci（8.6%） with blood signals of grade 1,19（54.3%） with that of grade 2 and 13（37.1%） with that of grade 3 in the PLC group,while there were 33 foci （82.5%） with blood signals of grade 0 and 7 （17.5%） with that of grade 1 in the FNH group （P<0.05）. Conclusion The ultrasound contrast and micro blood flow imaging could distinguish atypical PLC and FNH by the characteristics of time phase,contrast enhancement and the hemodynamic changes.

Key words: Hepatoma, Focal nodular hyperp-lasia, Ultrasound contrast, Micro blood flow imaging, Differential diagnosis