Breast lesions: Evaluation with US strain imaging-clinical experience of multiple observers

Purpose: To prospectively determine the accuracy of using an ultrasonographic (US) strain imaging technique known as lesion size comparison to differentiate benign from malignant breast lesions. Materials and Methods: Institutional Review Board approval and patient informed consent were obtained for this HIPPA-compliant study. US strain imaging was performed prospectively for 89 breast lesions in 88 patients. Lesions were imaged by using free-hand compression and a real-time strain imaging algorithm. Five observers obtained manual measurements of lesion height, width, and area from B-mode and strain images. By using these size measurements, individual observer and group performances were assessed by using the area under the receiver operating characteristic curve (A_z). The performance of a single size parameter versus that of a combination of size parameters was evaluated by using univariate and multivariate logistic regression. Results: Group A_z values showed that width ratio and area ratio yielded the best results for differentiating benign and malignant breast lesions, and they were not statistically different from one another (P = .499). For the group, the performance of area and width, which was superior to that of height and aspect ratio, was stastically significant for all cases (P < .011) except for those that compared area with aspect ratio (P = .118). By using a group threshold of 1.04 for width ratio and 1.13 for area ratio, the sentivity and specificity of the technique were 96% and 21%, respectively, for width 96% and 24%, respectively, for area. The best observer achieved a sensitively of 96% and a specificity of 61% by using the area ratio. For all but one observer performance (P > .258). Significant interobserver performance variability was observed (P < .001). Conclusion: Results suggest that US strain imaging has the potential to aid diagnosis of breast lesions. However, manually tracing lesion boundaries for size ratio differentiation in a busy clinical setting did not match the diagnostic performance levels previously reported. Focusing on measurements of lesion width, along with additional observer training or automated processes, may yield a suitable method for routine clinical application.