Diagnostic Performance and Additional Value of Elastosonography in Focal Breast Lesions: Statistical Correlation between Size-Dependant Strain Index Measurements, Multimodality-BI-RADS Score, and Histopathology in a Clinical Routine Setting
Objective. To evaluate the diagnostic benefit of real-time elastography (RTE) in clinical routine. Strain indices (SI) for benign and malignant tumors were assessed. Methods. 100 patients with 110 focal breast lesions were retrieved. Patients had mammography (MG), ultrasound (US), and, if necessary, MRI. RTE was conducted after ultrasound. Lesions were assessed with BI-RADS for mammography and ultrasound. Diagnosis was established with histology or follow-up. Results. SI for BI-RADS 2 was . Higher SI was observed for BI-RADS 3 lesions. SI of BI-RADS 4 and 5 lesions were significantly higher and . 31 malignant tumors exhibited an average SI of ; SI of benign lesions was ( value ). ROC analysis threshold was >3.8 for malignant disease. Sensitivity of sonography was 90.3% (specificity 78.5%). RTE showed a sensitivity of 87.1% (specificity 79.7%). Accuracy of all modalities combined was 96.8%. In BI-RADS 3 lesions RTE was able to detect all malignant lesions (sensitivity 100%, specificity 92.9%, and accuracy 93.9%). Conclusions. RTE increased sensitivity and specificity for breast cancer detection when used in combination with ultrasound. 1. Introduction Breast cancer is one of the most common cancers occurring in women [1], but sensitive diagnostic imaging modalities that detect cancer early are frequently limited by their low specificity. In addition to digital mammography, ultrasound has been established as a valuable tool for making early diagnoses, especially for focal masses in dense breast glands [2]. The first clinical uses of real-time strain elastography for mammary lesions were described between 1997 and 2003 [3–5]. Real-time elastography (RTE) can be rapidly and easily performed along with a B-scan and Doppler ultrasound during the same session. This procedure can aid in identifying the lesion’s morphological features and in obtaining information regarding the tissue’s mechanical characteristics [6]. Itoh et al. [7] established a scoring system to morphologically classify lesions in a manner analogous to the Breast Imaging and Reporting Data System (BI-RADS) [8]. RTE can be used to monitor mechanical tissue properties via an ultrasound probe that calculates the strain produced by an externally applied force. Using the combined autocorrelation method (CAM), data regarding tissue displacement prior to and following the compression is measured and merged with the conventional B-mode image [7, 9]. In addition to the morphological information, the result of these two measurements is the so-called “strain index,” representing a semiquantitative
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