The Study Of Acoustic Radiation Force Impulse(ARFI)Technology On The Differential Diagnosis Of Breast Lesions

Purpose:To study the tissue stiffness of different types of breast lesions by applying the elastographic quantification technology of acoustic radiation force impulse (ARFI) technology and determine whether the new technology could improve the diagnostic performance of differentiating between benign and malignant breast masses.Materials and methods:From September2011to December2012,145female patients with151breast lesions were enrolled in the prospective study. B-mode ultrasonography, color Doppler ultrasonography, and ARFI were consecutively conducted by one experienced investigator on Siemens ACUSON S2000ultrasound system unit. The investigator blinded to histopathologic findings made the assessment on the B-mode imaging data according to ACR US BI-RADS classification criteria. The elatographic assessment was based on area ratio. The values of shear wave velocities of breast lesions were obtained by using ARFI technology (Virtual Touch tissue quantification, Siemens), including the internal and marginal areas of target lesion, the surrounding mammary gland1(<1cm distant from the margin of lesion), the surrounding mammary gland2(1-4cm distant from the margin of lesion), contralateral mammary gland and subcutaneous fat. All the patients finally underwent operation and the histopathologic results were available. Histopathology was served as the golden standard:60benign and91malignant. Statistical analyses were performed with SPSS version16.0software. The receiver operative curve is used to evaluate the diagnostic performance of different technology. P<0.05was considered statistically significant in our study.Results:1. The mean SWV in subcutaneous fat and mammary gland were (1.28±0.62) m/s and(2.08±0.43)m/s, respectively.(P<0.05) The mean SWV of mammary gland in the premenopausal group and the postmenopausal group were (2.05±0.36)m/s and (1.96±0.4)m/s, respectively.(P>0.05)2. The malignant masses were significantly harder than the benign masses by using ARFI measurement in internal areas(6.20±2.44m/s vs2.47±0.97m/s, p<0.05), marginal areas (4.52±1.34m/s vs2.29±0.51m/s, p<0.05) and the surrounding1(1.96±0.46m/s vs2.48±0.80m/s, p<0.05). There were no significant differences between benign and malignant lesions in both surrounding2(1.99±0.43m/s vs1.96±0.41m/s,P>0.05) and contralateral mammary gland(2.05±0.39m/s vs1.97±0.38m/s,p>0.05). Moreover, statistical significances were found in the "internal value ratio"(internal area of target lesion/contralateral mammary)(1.22±0.46vs3.21+1.34,P<0.05)and "marginal value ratio"(internal area of target lesion/contralateral mammary)(2.34±0.83vs1.13±0.26, p<0.05) between benign and malignant lesions.3. When the "internal value" of3.18m/s was chosen as the cutoff point, the sensitivity, specificity and accuracy were90.1%,91.7%and90.7%, respectively. When the "marginal value" of3.01m/s was chosen as the cutoff point, the sensitivity, specificity and accuracy were89.0%,91.7%and90.1%,respectively. When the "internal value ratio" of2.00was chosen as the cutoff point, the sensitivity, specificity and accuracy were81.3%,96.7%and87.4%, respectively. When the "marginal value ratio" of1.45was chosen as the cutoff point, the sensitivity, specificity and accuracy were92.3%,91.7%and92.1%,respectively. The sensitivity of "internal value ratio" was lower than the others, the specificity and accuracy was close to each other among them. There was no statistically differences among the AUC of internal value, marginal value, internal value ratio and marginal value ratio (0.931vs0.955vs0.925vs0.955,p>0.05).4. Considering BI-RADS category4a or higher as test positive for malignancy, the sensitivity, specificity, and accuracy were95.6%,85.0%,91.4%, respectively. By addition of shear wave velocity ratio of marginal area, the modified BI-RADS category4A and4B improved the specificity from85.0%to95.0%(P<0.05) and resulted the unchanged sensitivity and accuracy (P<0.05).Conclusion:1. All the four diagnostic parameters including the internal tissue SWV, the marginal tissue SWV, the internal tissue SWV ratio and the marginal tissue SWV ratio have excellent performance in the diagnosis of breast lesions.2. The new technology could be a useful supplement to the conventional ultrasonography in differential diagnosis of benign and malignant breast lesions by improving the specificity obviously.