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Shearwave Elastography Increases Diagnostic Accuracy in Characterization of Breast Lesions

View Article: PubMed Central - PubMed

ABSTRACT

The purpose of this study was to investigate the diagnostic efficacy of shearwave elastography (SWE) in differentiating between benign and malignant breast lesions.

One hundred and fifty-nine lesions were assessed using B-mode ultrasound (US) and SWE parameters were recorded (Emax, Emean, Emin, Eratio, SD). SWE measurements were then correlated with histopathological diagnosis.

≥≥: The final sample contained 85 benign and 74 malignant lesions. The maximum stiffness (Emax) with a cutoff point of 56.0 kPa (based on ROC curves) provided sensitivity of 100.0%, specificity of 97.6%, positive predictive value (PPV) of 97.4%, and negative predictive value (NPV) of 100% in detecting malignant lesions. A cutoff of 80 kPa managed to downgrade 95.5% of the Breast Imaging-Reporting and Data System (BI-RADS) 4a lesions to BI-RADS 3, negating the need for biopsy. Using a combination of BI-RADS and SWE, the authors managed to improve the PPV from 2.3% to 50% in BI-RADS 4a lesions.

SWE of the breast provides highly specific and sensitive quantitative values that are beneficial in the characterization of breast lesions. Our results showed that Emax is the most accurate value for differentiating benign from malignant lesions.

No MeSH data available.


Related in: MedlinePlus

Quantitative measurements: A circular ROI of 2-mm diameter was placed at the area of maximum stiffness of the lesion with another ROI placed at the normal breast tissue at the same depth. Emean is the mean elasticity of the lesion, Emin is the minimum elasticity of the lesion, Emax is the maximum elasticity of the lesion, and SD is the standard deviation of the results. SWE ratio is the ratio of the lesion to the normal tissue. Qualitative measurements: Shape, homogeneity of lesion.
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Figure 1: Quantitative measurements: A circular ROI of 2-mm diameter was placed at the area of maximum stiffness of the lesion with another ROI placed at the normal breast tissue at the same depth. Emean is the mean elasticity of the lesion, Emin is the minimum elasticity of the lesion, Emax is the maximum elasticity of the lesion, and SD is the standard deviation of the results. SWE ratio is the ratio of the lesion to the normal tissue. Qualitative measurements: Shape, homogeneity of lesion.

Mentions: All scans were performed using the Aixplorer ultrasound system (SuperSonic Imagine, Aix en Provence, France) using a 15-4 MHz linear transducer probe. Two radiologists specializing in breast imaging were responsible for scanning the patients (FF and KR with 4 and 10 years of experience, respectively). Both radiologists were blinded to the histological diagnosis. The study protocol was formulated and standardized after performing an initial pilot study in accordance to previous literature.6–10 The US examination initially produced Standard B-mode gray scale images, and generated elastography images after an extra 3 to 5 minutes. A 3 × 3 cm color map in transverse plane was placed on the region encompassing the lesion and its immediate surrounding tissues. The probe was held stationary with no added pressure over the region of interest (ROI) during the SWE measurements. A circular ROI with a diameter of 2 mm was placed at the center of the lesion to attain a color map. The 2-mm diameter was chosen in line with other recently published studies.9,10 Real-time shearwave images were captured after viewing the color map. The color map provided a visual representation of tissue stiffness, with different shades of a spectrum of colors: blue for softer tissues and red for harder tissues. The ROI's SWE readings consisted of maximum elasticity (Emax), mean elasticity (Emean), minimum elasticity (Emin), and ratio of lesion to surrounding tissue (Eratio), with their standard deviations (SD). The color map was also represented numerically with lower values corresponding to softer tissues, that is, blue, and higher values to harder tissues, that is, red (Figure 1). The range of the color scale was 0 to 180 kPa. The lower limit of the chromatic scale was adjusted to 180 kPa to display evident differences in tissue stiffness based on the color map; this setting is regarded as the calibrated optimum scale for breast study as per the manufacturer's recommendation. However, the quantitative measurement scale was set at a maximum of 300 kPa.


Shearwave Elastography Increases Diagnostic Accuracy in Characterization of Breast Lesions
Quantitative measurements: A circular ROI of 2-mm diameter was placed at the area of maximum stiffness of the lesion with another ROI placed at the normal breast tissue at the same depth. Emean is the mean elasticity of the lesion, Emin is the minimum elasticity of the lesion, Emax is the maximum elasticity of the lesion, and SD is the standard deviation of the results. SWE ratio is the ratio of the lesion to the normal tissue. Qualitative measurements: Shape, homogeneity of lesion.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4998391&req=5

Figure 1: Quantitative measurements: A circular ROI of 2-mm diameter was placed at the area of maximum stiffness of the lesion with another ROI placed at the normal breast tissue at the same depth. Emean is the mean elasticity of the lesion, Emin is the minimum elasticity of the lesion, Emax is the maximum elasticity of the lesion, and SD is the standard deviation of the results. SWE ratio is the ratio of the lesion to the normal tissue. Qualitative measurements: Shape, homogeneity of lesion.
Mentions: All scans were performed using the Aixplorer ultrasound system (SuperSonic Imagine, Aix en Provence, France) using a 15-4 MHz linear transducer probe. Two radiologists specializing in breast imaging were responsible for scanning the patients (FF and KR with 4 and 10 years of experience, respectively). Both radiologists were blinded to the histological diagnosis. The study protocol was formulated and standardized after performing an initial pilot study in accordance to previous literature.6–10 The US examination initially produced Standard B-mode gray scale images, and generated elastography images after an extra 3 to 5 minutes. A 3 × 3 cm color map in transverse plane was placed on the region encompassing the lesion and its immediate surrounding tissues. The probe was held stationary with no added pressure over the region of interest (ROI) during the SWE measurements. A circular ROI with a diameter of 2 mm was placed at the center of the lesion to attain a color map. The 2-mm diameter was chosen in line with other recently published studies.9,10 Real-time shearwave images were captured after viewing the color map. The color map provided a visual representation of tissue stiffness, with different shades of a spectrum of colors: blue for softer tissues and red for harder tissues. The ROI's SWE readings consisted of maximum elasticity (Emax), mean elasticity (Emean), minimum elasticity (Emin), and ratio of lesion to surrounding tissue (Eratio), with their standard deviations (SD). The color map was also represented numerically with lower values corresponding to softer tissues, that is, blue, and higher values to harder tissues, that is, red (Figure 1). The range of the color scale was 0 to 180 kPa. The lower limit of the chromatic scale was adjusted to 180 kPa to display evident differences in tissue stiffness based on the color map; this setting is regarded as the calibrated optimum scale for breast study as per the manufacturer's recommendation. However, the quantitative measurement scale was set at a maximum of 300 kPa.

View Article: PubMed Central - PubMed

ABSTRACT

The purpose of this study was to investigate the diagnostic efficacy of shearwave elastography (SWE) in differentiating between benign and malignant breast lesions.

One hundred and fifty-nine lesions were assessed using B-mode ultrasound (US) and SWE parameters were recorded (Emax, Emean, Emin, Eratio, SD). SWE measurements were then correlated with histopathological diagnosis.

≥≥: The final sample contained 85 benign and 74 malignant lesions. The maximum stiffness (Emax) with a cutoff point of 56.0 kPa (based on ROC curves) provided sensitivity of 100.0%, specificity of 97.6%, positive predictive value (PPV) of 97.4%, and negative predictive value (NPV) of 100% in detecting malignant lesions. A cutoff of 80 kPa managed to downgrade 95.5% of the Breast Imaging-Reporting and Data System (BI-RADS) 4a lesions to BI-RADS 3, negating the need for biopsy. Using a combination of BI-RADS and SWE, the authors managed to improve the PPV from 2.3% to 50% in BI-RADS 4a lesions.

SWE of the breast provides highly specific and sensitive quantitative values that are beneficial in the characterization of breast lesions. Our results showed that Emax is the most accurate value for differentiating benign from malignant lesions.

No MeSH data available.


Related in: MedlinePlus