Tissue doppler and strain imaging for evaluating tissue elasticity of breast lesions

Aim: Sonoelastography depicts the intrinsic elastic properties of a tissue which are characterized by the strain applied to achieve tissue deformation and the velocity at which tissue deformation occurs. The present study served to investigate whether the specificity of B-mode ultrasound (US) can be improved by combining B-mode imaging with tissue Doppler imaging (TDI) and offline analysis of tissue strain imaging (TSI).

Methods: 25 with malignant and 25 with benign focal breast lesions were examined by US with a linear transducer (9MHz, Aplio, Toshiba). B-mode US views of the lesions were overlaid with color-coded TDI information and area quotients (AQ=area B-mode view/area TDI) were calculated. TSI views were reconstructed offline from the source data. This was done by placing a ROI in the target lesion and color-encoded display of the information. Maximum strain (strain factor, SF) was determined in the ROI. Sensitivities and specificities were calculated and statistical analysis was performed using Wilcoxon's test.

Results: Sensitivity/specificity was 96%/68% for B-mode US, 100%/40% for combined B-mode US and mammography, and 96%/80% for TSI. The AQ of benign and malignant lesions was significantly different (p=.00008) as was the difference in SF (p=.0004).

Conclusions: Evaluation of elasticity based on the quantification of strain factors improves characterization of focal breast lesions, especially the differentiation of BI-RADS 3 and 4 lesions. Significant results in characterizing breast lesions were obtained with the simple technique of TDI, showing a lower tissue displacement in malignant cases.