Elastic Modulus and Elasticity Ratio of Malignant Breast Lesions with Shear Wave Ultrasound Elastography: Variations with Different Region of Interest and Lesion Size.

Antonio Bulum,Marko Lucijanić,Gordana Ivanac,Kristina Bojanić,Iva Biondić Špoljar,Boris Brkljačić,Eugen Divjak,Martina Džoić Dominković

doi:10.3390/diagnostics11061015

Abstract

Shear wave elastography (SWE) is a type of ultrasound elastography with which the elastic properties of breast tissues can be quantitatively assessed. The purpose of this study was to determine the impact of different regions of interest (ROI) and lesion size on the performance of SWE in differentiating malignant breast lesions. The study included 150 female patients with histopathologically confirmed malignant breast lesions. Minimal (Emin), mean (Emean), maximal (Emax) elastic modulus and elasticity ratio (e-ratio) values were measured using a circular ROI size of 2, 4 and 6 mm diameters and the lesions were divided into large (diameter ≥ 15 mm) and small (diameter < 15 mm). Highest Emin, Emean and e-ratio values and lowest variability were observed when using the 2 mm ROI. Emax values did not differ between different ROI sizes. Larger lesions had significantly higher Emean and Emax values, but there was no difference in e-ratio values between lesions of different sizes. In conclusion, when measuring the Emin, Emean and e-ratio of malignant breast lesions using SWE the smallest possible ROI size should be used regardless of lesion size. ROI size has no impact on Emax values while lesion size has no impact on e-ratio values.

Highlights

Ultrasound elastography is an ultrasound technology which detects malignant breast lesions by measuring the changes of the elastic properties of breast tissue
Since most measurements were non-normally distributed, we presented all numerical variables as median and interquartile range (IQR) and used non-parametrical statistical tests
region of interest (ROI) is used to measure the lower elasticity values of the surrounding tissues that are not influenced by the malignant lesion, the effect on the measured Emin and e-ratio is the same as on the measured Emean values

Summary

Introduction

Ultrasound elastography is an ultrasound technology which detects malignant breast lesions by measuring the changes of the elastic properties of breast tissue. SWE is a type of ultrasound elastography where the elastic properties of breast tissue can be both qualitatively and quantitatively assessed. The velocity of shear waves can be measured and is proportional to tissue elasticity, allowing elastic modulus to be calculated. These values can be color-coded in various colors ranging between red and dark blue, which are superimposed over the gray-scale image in real time (so-called elastogram) [6]. The elastic modulus is measured using a region of interest (ROI) circle that is positioned over the examined lesion in the breast, and a second ROI is positioned over the surrounding fatty tissue to calculate the e-ratio value between the two. The studies differed in methodology in regard to the ROI size, from using a ROI size of 1 mm to encompassing the entire lesion [8,9,10]

Objectives

Methods

Conclusion