2D-SWE of the Breast: Stiffness Thresholds in kPa for Revising BI-RADS Category
The presented fragments consider 2D-SWE (shear wave elastography) as a method for quantitatively assessing the stiffness of breast lesions, complementing conventional ultrasound and potentially influencing BI-RADS categorization. Malignant lesions exhibit higher shear wave speeds (higher stiffness in kPa) because waves propagate faster in harder tissue.
Technical Parameters of the Scale
Shear waves are generated by an automated "push pulse" transducer: longitudinal displacement of the lesion induces transverse waves, the speed of which is recorded by the system. For mammological applications, the maximum scale is often set at 7.7 m/s (180 kPa) (Diagnostic Imaging: Breast, 3rd ed., 2019).
Threshold for Revising BI-RADS 3 Category
According to EFSUMB (Cosgrove et al., 2013), additional 2D-SWE features support the possibility of downgrading BI-RADS 3 category, as described by the BE-1 group. With benign 2D-SWE data, this allows for improved diagnostic efficiency by reducing unnecessary short-term dynamic monitoring of BI-RADS 3 lesions — especially with maximum elasticity < 20 kPa.
| Parameter | Value from Fragments | Source |
|---|---|---|
| Emax for Downgrading BI-RADS 3 | < 20 kPa (benign 2D-SWE data) | EFSUMB, Cosgrove et al., 2013 |
| Maximum Scale for Breast | 7.7 m/s (180 kPa) | Diagnostic Imaging: Breast, 2019 |
| Emean Threshold (average) | [to be clarified] — not present in fragments | — |
Data on Prognostic Significance
The fragments mention the work of Berg WA et al. (AJR Am J Roentgenol, 2015) on the quantitative maximum shear stiffness of breast lesions as a predictor of histopathological severity; specific threshold values in kPa are not provided in the text [to be clarified].
Limitations from Fragment Data
The sources present only the threshold for Emax (< 20 kPa) concerning the downgrading of BI-RADS 3. Numerical thresholds for Emean/Emean in kPa, as well as separate criteria for downgrading BI-RADS 4A/4B, are absent in the provided fragments [to be clarified]. For strain elastography, a separate indicator is provided — E/B ratio (most accurate by meta-analysis: sensitivity 96%, specificity 88%, with potential downgrading of BI-RADS 4A and even 4B to BI-RADS 3 at malignancy rate < 2%), however, this pertains to compression, not 2D-SWE methodology.
The final BI-RADS category is assigned based on the entire picture; elastography data serve as a supplement to conventional ultrasound, not a replacement for comprehensive assessment.
Frequently asked questions
At what Emax value can BI-RADS 3 be downgraded?
According to EFSUMB (Cosgrove et al., 2013) — with benign 2D-SWE data, especially with maximum elasticity < 20 kPa; this allows for reducing unnecessary short-term follow-up.
What is the maximum scale to set for the breast?
For mammological applications, the maximum scale is often set at 7.7 m/s (180 kPa) (Diagnostic Imaging: Breast, 2019).
Are there thresholds for Emean in the fragments?
No. Specific threshold values for Emean in kPa are not provided in the fragments [to be clarified]. Only the Emax threshold < 20 kPa is mentioned.
Can 2D-SWE be used to downgrade BI-RADS 4A/4B?
In the fragments, downgrading 4A/4B to BI-RADS 3 is described for strain elastography (E/B ratio, malignancy rate < 2%). For 2D-SWE, only downgrading category 3 is indicated [to be clarified].
Does 2D-SWE replace conventional ultrasound in categorization?
No. 2D-SWE complements conventional ultrasound to enhance diagnostic efficiency; the final category is assigned based on the entire set of features.