Value of diffusion weighted MR imaging in the differential diagnosis of benign and malignant breast lesions:affirmation of ADC cut-off value as b value equals to 800s/mm~2

Objective:To affirm the cut-off value of apparent diffusion coefficient(ADC) when b value=800s/mm2 in the differential diagnosis of benign or malignant breast lesions,and to evaluate the diffusion weighted MR imaging(DWI) in the diagnosis of breast diseases.Methods:Bilateral breast axial DWI were performed in seventy female patients(78 lesions) having surgery and histo-pathology proven breast lesions,with benign(26 cases,31 lesions) and malignant(44 cases,47 lesions).and the imaging materials were retrospectively analyzed.The ADC values of all breast lesions were calculated and its threshold of differentiating benign or malignant lesions was affirmed with receiver operating characteristic curve(ROC),area under ROC was calculated as well.Results:Twenty-nine benign lesions(29/31) and forty-seven malignant lesions(47/47) were visible on DWI.The ADC values of benign and malignant lesions were(1.46±0.26)×10-3mm2/s and(1.02±0.19)×10-3mm2/s respectively.The ADC value of malignant lesions were markedly lower than that of benign lesions,with significant statistical difference(P0.05).The threshold between benign and malignant lesions was 1.28×10-3mm2/s by the method of Youden index maximum,with the sensitivity,specificity,and accuracy as 93.6%,75.9%,and 86.8%,respectively.The threshold was 1.035×10-3mm2/s by the method of positive likelihood ratio maximum according to ROC,with the sensitivity,specificity,and accuracy as 46.8%,96.6%,and 65.8%,respectively.Area under ROC was 0.905(95% confidence interval was 0.836~0.975).Conclusion:When b value=800s/mm2,the cut-off value of ADC in differentiating diagnosis benign or malignant breast lesions was affirmed as 1.28×10-3mm2/s.Measurement of ADC value on DWI is an effective parameter in the diagnosis of benign and malignant breast lesions.