Summary of Dr. Berg Radiology 2012

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.


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


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.


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


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


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)


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


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




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


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




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


Addition of Ecol to BI-RADS assessments alone

for oval and circumscribed masses

The end

Health & Medicine

Summary of Dr. Berg Radiology 2012