Evaluation of breast stiffness measured by ultrasound and breast density measured by MRI using a prone-supine deformation model

Jeon-Hor Chen,Shunshan Li,Siwa Chan,Min-Ying Su,Ruey-Feng Chang,Yang Zhang

doi:10.1186/s40364-019-0171-1

Abstract

BackgroundThis study evaluated breast tissue stiffness measured by ultrasound elastography and the percent breast density measured by magnetic resonance imaging to understand their relationship.MethodsMagnetic resonance imaging and whole breast ultrasound were performed in 20 patients with suspicious lesions. Only the contralateral normal breasts were analyzed. Breast tissue stiffness was measured from the echogenic homogeneous fibroglandular tissues in the central breast area underneath the nipple. An automatic, computer algorithm-based, segmentation method was used to segment the whole breast and fibroglandular tissues on three dimensional magnetic resonanceimaging. A finite element model was applied to deform the prone magnetic resonance imaging to match the supine ultrasound images, by using the inversed gravity loaded transformation. After deformation, the tissue level used in ultrasound elastography measurement could be estimated on the deformed supine magnetic resonance imaging to measure the breast density in the corresponding tissue region.ResultsThe mean breast tissue stiffness was 2.3 ± 0.8 m/s. The stiffness was not correlated with age (r = 0.29). Overall, there was no positive correlation between breast stiffness and breast volume (r = − 0.14), or the whole breast percent density (r = − 0.09). There was also no correlation between breast stiffness and the local percent density measured from the corresponding region (r = − 0.12).ConclusionsThe lack of correlation between breast stiffness measured by ultrasound and the whole breast or local percent density measured by magnetic resonance imaging suggests that breast stiffness is not solely related to the amount of fibroglandular tissue. Further studies are needed to investigate whether they are dependent or independent cancer risk factors.

Highlights

Breast connective and epithelial tissues attenuate x-ray more than fat and show higher signal intensity than fat on mammography, an appearance that is referred to as “mammographic densities.” Mammographic density (MD) is a well-documented risk factor for developingBreast stiffness, reflecting the physical forces generated by interactions between cells, and between cells and the extracellular matrix, influences a variety of cell functions including cell growth, survival, motility and differentiation [4]
Reproducibility of breast stiffness measurement To determine the reproducibility of the breast stiffness measures using US, the experienced US technician selected three to five Region of interest (ROI) at the different locations but comparable depth of the breast which showed dense tissue
Nine patients had coefficient of variation (CV) below 10%, eight patients showed CV between 10 and 20%, and three patients had CV more than 20%

Summary

Introduction

Breast stiffness, reflecting the physical forces generated by interactions between cells, and between cells and the extracellular matrix, influences a variety of cell functions including cell growth, survival, motility and differentiation [4]. In normal mammary epithelial cells, increasing extracellular matrix (ECM) stiffness alone induces malignant phenotypes [6]. A recent study [7] noted that an estimate of breast tissue stiffness, derived from measurements of the volume and the projected area of the compressed breast during mammography, was associated with breast cancer risk and could be used to improve risk prediction. Molecules that mediate the influence of the ECM and the stiffness of stroma, and how they are associated with breast cancer, are being investigated [8, 9]. This study evaluated breast tissue stiffness measured by ultrasound elastography and the percent breast density measured by magnetic resonance imaging to understand their relationship

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