Effects of precompression on elasticity imaging of the breast: development of a clinically useful semiquantitative method of precompression assessment.

OBJECTIVES: Elastography of the breast is a new technique for characterization of breast lesions. The reproducibility of elastographic techniques has been questioned. Precompression is known to effect elastographic results. This study determined the effect of precompression on clinical images and proposes a method to semiquantify the amount of precompression applied.
METHODS: Ten patients with different breast tissue types were evaluated with shear wave and strain elastography with varying amounts of precompression. The changes in the shear wave speed and images were documented. A semiquantitative method for determining the amount of precompression applied is presented. The reproducibility of the technique was determine by repeated measurements by 3 sonographers.
RESULTS: Precompression substantially changes the elastographic results of patient images on both strain and shear wave elastography. Fat can have the same elasticity as cancer with clinically possible amounts of precompression. The proposed method for determining the amount of precompression applied has variability of less than 10%, which is within the error of the technique and would not affect clinical results. Four zones of precompression are identified, which are useful for explaining the effects of precompression on both strain and shear wave imaging.
CONCLUSIONS: Precompression is a substantial factor in obtaining accurate results with elastography. A proposed simple, easily applied technique can be used to semiquantify the amount of precompression applied. Precompression should be minimized in obtaining breast clinical images.