Characterisation of indeterminate focal breast lesions on grey-scale ultrasound: role of ultrasound elastography.

PURPOSE: This study was undertaken to evaluate the role of ultrasound (US) elastography in characterising focal breast lesions classified as indeterminate on B-mode US. MATERIALS AND METHODS: Eighty-four focal breast lesions, 64 benign and 20 malignant (mean diameter, 15.1 mm), detected but not characterised on B-mode US in 72 women, Breast Imaging Reporting and Data System (BI-RADS) US category 3 (n=56) or category 4 (n=28), were studied with US elastography and classified in consensus by two radiologists according to a five-point colour scale. Sensitivity, specificity and positive and negative predictive values (PPV and NPV) of US elastography compared with conventional US were calculated in relation to microhistology (n=67) and cytology (n=17), which were used as the reference standard. RESULTS: A total of 65/84 (77.4%) lesions were correctly classified as benign or malignant using US elastography, whereas the remaining 19/84 (22.6%) were incorrectly assessed. There were no statistically significant differences between US elastography and B-mode US with regard to sensitivity (70% vs. 68.4%), specificity (79.6% vs. 78.5%), PPV (51.8% vs. 48.1%) and NPV 89% vs. 89.5% (p>0.5). By contrast, a statistically significant difference was noted in the evaluation of BI-RADS 3 lesions, in which US elastography had 50% sensitivity, 86% specificity, 30% PPV and 93.5% NPV compared with BI-RADS 4 lesions (78.6%, 57.1%, 64.7% and 72.7%) (p<0.5). CONCLUSIONS: The high NPV of US elastography may help reduce the use of biopsy in BI-RADS 3 lesions, but its low PPV in BI-RADS 4 lesions does not allow avoidance of biopsy on the basis of the US elastographic score alone in this group of lesions.