Jung Min Chang MD, Presenter: Nothing to Disclose

Woo Kyung Moon, Abstract Co-Author: Nothing to Disclose

Nariya Cho MD, Abstract Co-Author: Nothing to Disclose

Seung Ja Kim, Abstract Co-Author: Nothing to Disclose

To prospectively compare the diagnostic performance of shear wave and static US elastography systems for differentiation of benign and malignant breast masses.

Between March 2010 and April 2010, 125 women (mean age 47 years, range 22 – 75 years) with 156 breast masses (mean size 19 mm, range 4-80 mm) (76 malignant, 80 benign) underwent US elastographic examinations with both systems (shear wave and static US elastography) by one radiologist prior to biopsy. Probability of malignancy based on conventional US findings was recorded prior to US elastography. With shear wave system, quantitative elasticity values in kiloPascal units measured was recorded. For static elastography, the elasticity score (1-5) based on the degree and distribution of strain proposed by Itoh et al. (Radiology 2006; 239:341–350) was given. Diagnostic performance of the two systems in distinguishing benign from malignant masses was compared using receiver operating characteristic (ROC) curve analysis and McNemar’s test using histological analysis as a reference standard.

The area under the ROC curve for the static elastography system (Az=0.948) was similar to that of the shear wave elastography system (Az=0.917) (difference between areas 0.02, 95% CI - 0.01-0.07, P=0.172). The best cut-off values, yielding the maximal sum of sensitivity and specificity, were between values in kiloPascal units of 57.7 and elasticity scores of 3 and 4. The sensitivity of the shear wave elastography system was higher than that of the static elastography system [98.7% (75 of 76) vs. 78.9% (60 of 76), P = 0.0001] and the specificity of the static elastography system was higher than that of the shearwave elastography system [96.3% (77 of 80) vs. 71.2% (57 of 80), P = 0.001].

Two systems showed similar overall diagnostic performance. However the shearwave elastography system showed better sensitivity, and the static elastography system showed better specificity with the certain fixed cutoff values in distinguishing benign from malignant breast masses.  

Understanding the characteristics of both shear wave elastography and static elastography systems can be helpful in optimizing the diagnostic criteria for each system.

Chang, J, Moon, W, Cho, N, Kim, S, Comparison of Commercially Available Shear Wave and Static US Elastography Systems for Differentiation of Benign and Malignant Breast Masses.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11007255.html