Differentiating Benign from Malignant Solid Breast Masses with US Strain Imaging

doi:10.1148/radiol.2452061805

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Breast Imaging

Differentiating Benign from Malignant Solid Breast Masses with US Strain Imaging¹

Elizabeth S. Burnside, MD, MPH, MS, Timothy J. Hall, PhD, Amy M. Sommer, MS, Gina K. Hesley, MD, Gale A. Sisney, MD, William E. Svensson, MD, Jason P. Fine, PhD, Jinfeng Jiang, PhD, and Nicholas J. Hangiandreou, PhD

¹ From the Departments of Radiology (E.S.B., G.A.S.) and Medical Physics (T.J.H., A.M.S., J.J.), University of Wisconsin Medical School, E3/311 Clinical Science Center, 600 Highland Ave, Madison, WI 53792-3252; Department of Radiology, Mayo Clinic, Rochester, Minn (G.K.H., N.J.H.); Department of Nuclear Medicine and Breast Imaging, Imperial College School of Medicine and Charing Cross Hospital, London, England (W.E.S.); and Department of Statistics and Neurology, University of Wisconsin, Madison, Wis (J.P.F.). Received October 19, 2006; revision requested December 3; revision received February 6, 2007; accepted March 16; final version accepted April 18. E.S.B., T.J.H., A.M.S., J.P.F., and J.J. supported by grant DAMD17-00-1-0596 from the U.S. Army Medical Research and Materiel Command. E.S.B., T.J.H., A.M.S., and J.J. supported by grant R01CA100373 from the National Institutes of Health. G.K.H., N.J.H., and W.E.S. supported in part by grants from Siemens Medical Solutions, Ultrasound Division. Address correspondence to E.S.B. (e-mail: eburnside{at}uwhealth.org).

Purpose: To prospectively evaluate the sensitivity and specificityof ultrasonographic (US) strain imaging for distinguishing betweenbenign and malignant solid breast masses, with biopsy results asthe reference standard.

Materials and Methods: The study was institutional review board approvedand HIPAA compliant. Informed consent was obtained from all participatingpatients. US strain imaging of 403 breast masses was performed. The50 malignant and 48 benign lesions (in patients aged 19–83years; mean age, 49 years ± 17 [standard deviation]) withthe highest quality were selected for the reader study. Three observersblinded to the pathologic outcomes first described the B-mode imagefindings by using US Breast Imaging Reporting and Data System descriptorsand derived a probability of malignancy. They then updated the probabilityby assessing strain images. Receiver operating characteristic (ROC)curves were constructed by using these probabilities. Areas underthe ROC curve, sensitivities, and specificities were calculated andcompared. Interobserver variability and the correlation between automatedand subjective image quality assessment were analyzed.

Results: The average area under the ROC curve for all three readersafter US strain imaging (0.903) was greater than that after B-modeUS alone (0.876, P = .014). With use of a 2% probability of malignancythreshold, strain imaging—as compared with B-mode US alone—hadimproved average specificity (0.257 vs 0.132, P < .001) and highsensitivity (0.993 vs 0.987, P > .99). Significant interobservervariability was observed (P < .001). The ability to assess strainimage quality appeared to correlate with the highest observer performance.

Conclusion: US strain imaging can facilitate improved classificationof benign and malignant breast masses. However, interobserver variabilityand image quality influence observer performance.