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Shear-wave Elastography Improves the Specificity of Breast US: The BE1 Multinational Study of 939 Masses,” published in Radiology 2012
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1 Summary of Berg et al. Radiology 2012; 262:435-449 SSID02661-01
ShearWave™ elastography improves the specificity of
breast ultrasound
Summary of the article “Shear-wave Elastography Improves the Specificity of Breast US: The BE1 Multinational Study of 939 Masses,” published in Radiology 2012; 262:435-449
by Berg WA, Cosgrove DO, Doré CJ, Skyba DM, Henry JP, Gay J, Cohen-Bacrie C; the BE1 Study Group.
2 Summary of Berg et al. Radiology 2012; 262:435-449 SSID02661-01
Purpose of the study
To determine if and which SWE™ parameters added to conventional BI-RADS® criteria improve the characterization of breast masses
Strong focus on the reclassification of the masses within categories 3 and 4a
• among BI-RADS® 3: better characterization of the 2% malignant masses in order to avoid delays for treatment
• among BI-RADS® 4a: better characterization of the benign lesions in order in order to replace biopsy by follow-up
3 Summary of Berg et al. Radiology 2012; 262:435-449 SSID02661-01
Take home messages (1/2)
1. Any of the SWE™ features increases the AUC* of BI-RADS® assessment alone
2. Emax is the best SWE parameter to add to conventional BI-RADS® criteria to improve characterization of breast masses
3. BI-RADS® 2, supposedly benign masses: remain BI-RADS 2 regardless of SWE
4. BI-RADS® 5, 4c, 4b, moderate-to-highly suspicious masses: remain BI-RADS 5, 4c, 4b regardless of SWE
*AUC: Area Under the ROC Curve. Indicative for both sensitivity and specificity. Values:1 perfect test; 0.5 useless test.
4 Summary of Berg et al. Radiology 2012; 262:435-449 SSID02661-01
Take home messages (2/2)
5. BI-RADS® 3 and 4a
Reclassification rules with Emax added to conventional BI-RADS® criteria
BI-RADS 3 + Emax≥ 160 kPa : upgrade the lesion to 4
Biopsy recommended
Delay avoided in the early management of malignant masses
BI-RADS 4a + Emax≤ 80 kPa : downgrade the lesion to 3
Follow-up recommended
Biopsy of benign masses avoided
BI-RADS 3 and 4a, subset of oval and circumscribed masses: Reclassification of low risk lesions with Ecol:
Sensitivity increases from 0% to 100% (p= 0.046) Specificity increases from 79.1% to 90.4% (p<0.001)
This excellent sensitivity allows to better identify the few malignant masses and to adapt the management without delay
5 Summary of Berg et al. Radiology 2012; 262:435-449 SSID02661-01
Materials and methods (1/2)
Participants, investigators and reviewer
These points are detailed in the document “Shear wave elastography is highly reproducible“ SSID02658-01
Statistics
C.J.Doré, BSC, independent statistical expert from Medical Research Council of the United Kingdom
Validation of the results with different statistical tools:
Fisher exact test, weighted k values, McNemar test, Mann-Whitney U test, Spearman rank correlation
6 Summary of Berg et al. Radiology 2012; 262:435-449 SSID02661-01
Imaging, information collected by the investigator and information collected
during the blind review: see the document SSID02658-01
The most relevant SWE™ features studied
• Qualitative SWE™ features of the lesion and the surrounding parenchyma
Esha: lesion shape Ehomo: homogeneity of the elasticity (or stiffness)
Ecol: maximum elasticity on a six-point color scale
• Quantitative SWE™ features of the lesion and surrounding parenchyma
Emax: maximum value of elasticity
For each participant
Materials and methods (2/2)
7 Summary of Berg et al. Radiology 2012; 262:435-449 SSID02661-01
Results (1/4)
Global performances improved
Addition of SWE™ features to conventional BI-RADS® assessments
BI-RADS® category 3 – 5
Any of the SWE features increases the AUC of BI-RADS assessment alone
Ecol: the best performing qualitative feature, AUC increased from 0.940 to 0.971
Emax the best performing quantitative feature, AUC increased from 0.940 to 0.962
Excellent correlation between qualitative Ecol and quantitative Emax
No improvement by adding more than one SWE feature
8 Summary of Berg et al. Radiology 2012; 262:435-449 SSID02661-01
Using B Mode criteria
Using B Mode criteria + E color
BIRADS 4a
of which 18 cancers
193
of which 18 cancers
78
BIRADS 3
303
of which 8 cancers
418
of which 8 cancers
Results (2/4)
Improved specificity, constant sensitivity
Ehom: same improvement in specificity with an insignificant decrease of sensitivity from 97.2% to 96.2%
Esha: significant improvement in specificity with an insignificant increase in sensitivity to 97.9%
Addition of Ecol to BI-RADS assessments alone
Reclassification of BI-RADS® 3 – 4a:
20 red suspicious upgraded 17 benign, 3 malignant
135 black or blue not suspicious downgraded 132 benign, 3 malignant
Specificity increases from 61.1% to 78.5% (397/650 to 512/650) p<0.0001. i.e. + 17%
PPV of biopsy for BI-RADS 4a: from 9.3% to 23% (18/193 to 18/78) i.e. + 14%
Rate of malignancy for BI-RADS 3: never worse than the 2.6% initially observed
9 Summary of Berg et al. Radiology 2012; 262:435-449 SSID02661-01
Using B Mode criteria
Using B Mode criteria + E color
BIRADS 4a
of which 18 cancers
193
of which 18 cancers
87
BIRADS 3
303
of which 8 cancers
409
of which 8 cancers
Results (3/4)
Improved specificity, constant sensitivity
Addition of Emax to BI-RADS assessments alone
Reclassification of BI-RADS® 3 – 4a:
33 ≥ 160 kPa suspicious upgraded 28 benign, 5 malignant
139 ≤ 80 kPa not suspicious downgraded 134 benign, 5 malignant
Specificity increases from 61.1% to 77.4% (397/650 to 503/650) p<0.001. i.e. + 16%
PPV of biopsy for BI-RADS 4a: from 9.3% to 20.7% (18/193 to 18/87) i.e. + 11%
Rate of malignancy for BI-RADS 3: 1.9%, better than the 2.6% initially observed
10 Summary of Berg et al. Radiology 2012; 262:435-449 SSID02661-01
Using B Mode criteria
Using B Mode criteria + E color
BIRADS 4a
of which 0 cancer
37
of which 4 cancers
17
BIRADS 3
144
of which 4 cancers
164
of which 0 cancer
28 black or blue not suspicious downgraded all benign
8 red suspicious upgraded 4benign, 4 malignant
Sensitivity increases from 0% to 100% (0/4 to 4/4) (p= 0.046)
Specificity increases from 79.1% to 90.4% (140/177 to 160 /177) (p<0.001) ) i.e. + 21%
Accuracy increases from 77.3% to 90.6% (140/181 to 164/181) (p<0.001) i.e. + 23%
Results (4/4)
Special benefits for low risk masses
Reclassification of BI-RADS® 3 – 4a:
Addition of Ecol to BI-RADS assessments alone
for oval and circumscribed masses
The end