<Diagnostic Value of Elastography Using Acoustic Radiation Force Impulse Imaging and Strain Ratio for Breast Tumors>

<Journal of Breast Cancer 2014 March; 17(1): 76-82>

Yoon Seok Kim, Jung Gu Park, Beom Su Kim, Chung Han Lee, Dong Won Ryu

Departments of Surgery and Radiology, Kosin University Gospel Hospital, Busan, Korea

Purpose
The aim of this study was to determine whether the combination of B-mode ultrasonography (BUS), acoustic radia-tion force impulse (ARFI) elastography, and strain ratio (SR) pro-vides better diagnostic performance of breast lesion differentia-tion than BUS alone.

Methods
ARFI elastography and SR evalu-ations were performed on patients with 157 breast lesions diag-nosed by BUS from June to September 2013. BUS images were classified according th the Breast Imaging-Reporting and Data System. ARFI elastography was performed using Virtual Touch™ tissue imaging (VTI) and Virtual Touch™ tissue quantification (VTQ). In VTI mode, we evaluated the color-mapped patterns of the breast lesion and surrounding tissue. The lesions were classi-fied into five categories by elasticity score. In VTQ mode, each lesion was assessed using shear wave velocity (SWV) measure-ments. SR was calculated from the lesion and comparable lateral fatty tissue. We compared the diagnostic performance of BUS alone and the combination of BUS, ARFI elastography, and SR evaluations.

​Results
Among the 157 lesions, 40 were malignant and 117 were benign. The mean elasticity score (3.7±1.0 vs. 1.6±0.8, p<0.01), SWV (4.23±1.09 m/sec vs. 2.22±0.88 m/sec, p<0.01), and SR (5.69±1.63 vs. 2.69±1.40, p<0.01) were signifi- cantly higher for malignant lesions than benign lesions. The re-sults for BUS combined with ARFI elastography and SR values were 97.5% sensitivity, 92.3% specificity, 93.6% accuracy, a 79.6% positive predictive value (PPV), and a 99.1% negative pre-dictive value. The combination of the 3 radiologic examinations yielded superioi specificity, accuracy, and PPV compared to BUS alone (p<0.01 for each).

Conclusion
ARFI elastography and SR evaluations showed significantly different mean values for benign and malignant lesions. Moreover, these two modalities comple-mented BUS and improved the diagnostic performance of breast lesion detection. Therefore, ARFI elastography and SR evalua-tions can be used as complementary modalities to make more accurate breast lesion diagnoses.

Key Words
Breast neoplasms, Elasticity imaging techniques, Ultrasonography