Quantitative shear wave ultrasound elastography: initial experience in solid breast masses

IntroductionShear wave elastography is a new method of obtaining quantitative tissue elasticity data during breast ultrasound examinations. The aims of this study were (1) to determine the reproducibility of shear wave elastography (2) to correlate the elasticity values of a series of solid breast masses with histological findings and (3) to compare shear wave elastography with greyscale ultrasound for benign/malignant classification.MethodsUsing the Aixplorer® ultrasound system (SuperSonic Imagine, Aix en Provence, France), 53 solid breast lesions were identified in 52 consecutive patients. Two orthogonal elastography images were obtained of each lesion. Observers noted the mean elasticity values in regions of interest (ROI) placed over the stiffest areas on the two elastography images and a mean value was calculated for each lesion. A sub-set of 15 patients had two elastography images obtained by an additional operator. Reproducibility of observations was assessed between (1) two observers analysing the same pair of images and (2) findings from two pairs of images of the same lesion taken by two different operators. All lesions were subjected to percutaneous biopsy. Elastography measurements were correlated with histology results. After preliminary experience with 10 patients a mean elasticity cut off value of 50 kilopascals (kPa) was selected for benign/malignant differentiation. Greyscale images were classified according to the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS). BI-RADS categories 1-3 were taken as benign while BI-RADS categories 4 and 5 were classified as malignant.ResultsTwenty-three benign lesions and 30 cancers were diagnosed on histology. Measurement of mean elasticity yielded an intraclass correlation coefficient of 0.99 for two observers assessing the same pairs of elastography images. Analysis of images taken by two independent operators gave an intraclass correlation coefficient of 0.80. Shear wave elastography versus greyscale BI-RADS performance figures were sensitivity: 97% vs 87%, specificity: 83% vs 78%, positive predictive value (PPV): 88% vs 84%, negative predictive value (NPV): 95% vs 82% and accuracy: 91% vs 83% respectively. These differences were not statistically significant.ConclusionsShear wave elastography gives quantitative and reproducible information on solid breast lesions with diagnostic accuracy at least as good as greyscale ultrasound with BI-RADS classification.

[1]  M. Fink,et al.  Supersonic shear imaging: a new technique for soft tissue elasticity mapping , 2004, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[2]  Thomas Deffieux,et al.  Quantitative assessment of breast lesion viscoelasticity: initial clinical results using supersonic shear imaging. , 2008, Ultrasound in medicine & biology.

[3]  T. Matsumura,et al.  Breast disease: clinical application of US elastography for diagnosis. , 2006, Radiology.

[4]  L. Liberman,et al.  Breast imaging reporting and data system (BI-RADS). , 2002, Radiologic clinics of North America.

[5]  Duane D. Meixner,et al.  Breast lesions: evaluation with US strain imaging--clinical experience of multiple observers. , 2006, Radiology.

[6]  M Heller,et al.  Breast ultrasound elastography--results of 193 breast lesions in a prospective study with histopathologic correlation. , 2011, European journal of radiology.

[7]  I. Ellis,et al.  The accuracy of breast ultrasound in the evaluation of clinically benign discrete, symptomatic breast lumps. , 1998, Clinical radiology.

[8]  M. Bani,et al.  Influence of mammographic density on the diagnostic accuracy of tumor size assessment and association with breast cancer tumor characteristics. , 2006, European journal of radiology.

[9]  E. Fleury,et al.  New elastographic classification of breast lesions during and after compression. , 2009, Diagnostic and interventional radiology.

[10]  Jason P Fine,et al.  Differentiating Benign from Malignant Solid Breast Masses with US Strain Imaging 1 , 2007 .

[11]  M. J. van de Vijver,et al.  Diagnosis of breast cancer: contribution of US as an adjunct to mammography. , 1999, Radiology.

[12]  M. Fink,et al.  Breast lesions: quantitative elastography with supersonic shear imaging--preliminary results. , 2010, Radiology.

[13]  Mickael Tanter,et al.  Multiwave imaging and super resolution , 2010 .

[14]  A. Stavros,et al.  Solid breast nodules: use of sonography to distinguish between benign and malignant lesions. , 1995, Radiology.

[15]  Differentiation of benign from malignant nonpalpable breast masses: A comparison of computer-assisted quantification and visual assessment of lesion stiffness with the use of sonographic elastography , 2010, Acta radiologica.

[16]  A. Stavros,et al.  US-guided automated large-core breast biopsy. , 1993, Radiology.