MR diffusion weighted imaging of mass or non-mass-like breast lesions on DCE-MRI:value of apparent diffusion coefficient in differential diagnosis of benign and malignant lesions

Objective:To assess the diagnostic value of apparent diffusion coefficient(ADC)and relative-ADC(rADC)in the diagnosis of breast mass and non-mass-like lesion.Methods:The MRI and DWI data of 177 patients with pathologically confirmed breast lesions were retrospectively analyzed.ADC and rADC of benign and malignant lesions were measured and compared(t-test),and receiver operating characteristic curve(ROC)analysis was used to evaluate the diagnostic performance of ADC and rADC in differentiating benign and malignant lesions.Results:Among 177 patients there were 112 benign and 65 malignant lesions;144were mass-like and 33 were non-mass-like.Among 144mass-like lesions,47 were malignant and 97 were benign.The mean ADC and rADC values of malignant lesions[(1.06±0.27)×10-3 mm2/s,0.62±0.17]were statistically lower than those of benign ones[(1.58±0.26)×10-3 mm2/s,0.91±0.17].The sensitivity and specificity of the ADC and rADC for diagnosis of malignant lesions with thresholds of 1.23×10-3 mm2/s and 0.72were85.1%、92.8% and 80.9%、89.7% respectively.Among 33non-mass lesions 18 were malignant and 15 were benign.The mean ADC value of malignant lesions [(1.25±0.40)×10-3 mm2/s]was statistically lower than that of benign lesions[(1.50±0.18)×10-3 mm2/s],while the mean rADC value of malignant lesions(0.76±0.25)was not statistically lower than that of benign lesions(0.89±0.12).The sensitivity and specificity of the ADC and rADC for diagnosis of malignant lesions with thresholds of 1.36×10-3 mm2/s and 0.84 were 77.8%,80.0% and 77.8%,73.3% respectively.Conclusion:The ADC is an effective parameter in distinguishing between malignant and benign breast lesions.Cut-off values of ADCs are different between breast masses and lesions with nonmasslike enhancement.The study indicated that ADC value is more valuable in differentiation of benign and malignant breast lesions than rADC value.