Objective To explore the correlation between contrast-enhanced ultrasound（CEUS） parameters and Ki-67 protein expression in prostate cancer.Methods Ninety-five prostate cancer patients diagnosed by rectal prostate biopsy were collected.Before operation

ultrasound contrast examination was performed to observe the ultrasound contrast mode and to determine the abnormal enhancement area

and the expression of Ki-67 protein in the abnormal enhancement area was detected by immunohistochemical.According to the results

they were divided into the negative group（40 cases）

low expression group（40 cases） and high expression group（15 cases）.The time-intensity curve of the abnormal enhancement region was analyzed by QLAB software

and the parameters of CEUS in each group were recorded and compared.The correlation between CEUS parameters and Ki-67 protein expression was analyzed.The receiver operating characteristic（ROC） curve was drawn to evaluate the diagnostic value of CEUS parameters for expression of Ki-67.Results The mode of contrast-enhanced ultrasound was dominated by heterogeneous enhancement

and the time-intensity curve of the abnormal enhancement area was dominated by rapid rise

rapid fall and slow rise.The area under curve（AUC）

peak intensity（PI）

the intensity halving time（HT）

mean transit time（MTT） and wash in slope of the ultrasound contrast time-intensity curve of each group were compared

and the differences were statistical significance（all P<0.05）

Among them

AUC

PI

HT and MTT were positively correlated with Ki-67 protein expression（r=0.657

0.537

0.503

0.407

all P<0.05）.ROC curve showed that AUC

PI and HT had high diagnostic value for Ki-67 expression levels.When the cutoff values were 479.44 dBs

7.71 dB and 49.48 s

the AUC were 0.848

0.793 and 0.752

respectively.The diagnostic specificity and sensitivity of AUC were the highest（83.64% and 73.24%）.Conclusion AUC

PI

HT of ultrasound contrast time-intensity curve and Ki-67 protein expression are correlated

which can provide a certain basis for noninvasive evaluation of the degree of tumor cell proliferation and tumor angiogenesis in prostate cancer

and can provide imaging reference for the prediction of turmor malignancy and prognosis.