David Owen Cosgrove MBBCh, FRCR, Presenter: Research Consultant, SuperSonic Imagine Research Consultant, Bracco Group Speakers Bureau, Toshiba Corporation

Wendie A. Berg MD, PhD, Abstract Co-Author: Research grant, Naviscan, Inc Researcher, Naviscan, Inc Speaker, SuperSonic Imagine Researcher, SuperSonic Imagine Medical Advisory Board, Koninklijke Philips Electronics NV Author, Gamma Medica Ideas, License, Merge Healthcare

Caroline Dore, Abstract Co-Author: Consultant, SuperSonic Imagine

Joel Gay, Abstract Co-Author: Employee, SuperSonic Imagine

Anthony Thomas Stavros MD, Abstract Co-Author: Clinical Advisory Board,SuperSonic Imagine Clinical Advisory Board, Devicor Medical Products, Inc Clinical Advisory Board, SonoCiné, Inc Clinical Advisory Board, General Electric Company Clinical Research, General Electric Company Clinical Research, The Medipattern Corporation Clinical Research, SuperSonic Imagine Shareholder, U-Systems, Inc

Ellen Bachman Mendelson MD, Abstract Co-Author: Scientific Advisory Board, Hologic, Inc Research support, Siemens AG Speakers Bureau, Siemens AG Medical Advisory Board, Quantason, LLC Consultant, Quantason, LLC Speakers Bureau, SuperSonic Imagine Research support, SuperSonic Imagine Medical Advisory Board, Toshiba Corporation

Fritz K.W. Schaefer MD, Abstract Co-Author: Nothing to Disclose

William Svensson MD, Abstract Co-Author: Equipment support, Siemens AG Speaker, Siemens AG Speaker, SuperSonic Imagine Research support, SuperSonic Imagine

To determine the diagnostic performance of SWE added to BI-RADS:US for subcentimeter masses.

Of 1647 women recruited to the HIPAA compliant BE1 study across 16 centers in Europe and the USA, 637 masses 10 mm and smaller were analyzable with reference standard of biopsy, FNAB (BI-RADS 4a, 4b, 4c, or 5), or at least one year follow-up (BI-RADS 3); BI-RADS 2 masses were presumed benign. After the routine scan, three SWE acquisitions were obtained for each mass using a prototype of the Aixplorer system (SuperSonic Imagine, Aix-en-Provence, France). A 2x2mm ROI was placed on the stiffest part of the mass using the color scale as a guide. The scale was preset to a maximum value of 180kPa and maximum elasticity recorded across 3 acquisitions (Emax). Threshold values were used to upgrade BI-RADS 3 masses to biopsy with Emax ≥160 and downgrade BI-RADS 4a masses to follow-up with Emax <80.

182 (28.6%) small masses were malignant. For 206 BI-RADS 3 masses (6, 3% malignant), higher malignancy rates were seen with higher Emax: 1% (2/170) for Emax <80, 7% (2/28) for Emax 80-<160 and 25% (2/8) for Emax ≥160 (p<.001). 26/187 (14%) BI-RADS 4a masses were malignant: 8/141 (6%) with Emax <80, 12/30 (40%) with Emax 80-<160 and 6/16 (38%) with Emax ≥160 (p=.001). For small masses specificity improved (p<0.001) from 247/455 (54.3%) for BI-RADS alone to 374/455 (82.2%) when SWE was considered, with slight loss of sensitivity (p=0.06) 176/182 (96.7%) vs 170/182 (93.4%). For large masses specificity improved (p<0.001) from 326/605 (53.9%) for BI-RADS alone to 427/605 (70.6%) with slight gain of sensitivity (p=0.18) 315/320 (98.4%) vs 318/320 (99.4%). For all masses, stiffness increased by 1.1 kPa per mm increase in size (0.80-1.42, p<0.001). Malignant masses averaged 88 kPa stiffer (83-93, p<0.001) than benign.

Small cancers ≤10 mm are significantly stiffer than small benign masses, but less stiff than larger malignancies. A few malignancies will be misclassified as benign-appearing by both BI-RADS and SWE, and this is more common with smaller masses than those >10mm.

An absolute increase in specificity of nearly 28% can be achieved when Emax is considered for BI-RADS 3 and 4a masses 10mm or smaller.

Cosgrove, D, Berg, W, Dore, C, Gay, J, Stavros, A, Mendelson, E, Schaefer, F, Svensson, W, Diagnostic Performance of Shearwave Elastography (SWE) Added to BI-RADS®: US for Masses ≤10mm.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11002865.html