Possible Focal Asymmetry

Presentation and Presenting Images


( ▶ Fig. 62.1, ▶ Fig. 62.2)


A 42-year-old female presents for screening mammography.


62.2 Key Images


( ▶ Fig. 62.3, ▶ Fig. 62.4)


62.2.1 Breast Tissue Density


The breasts are heterogeneously dense, which may obscure small masses.


62.2.2 Imaging Findings


The patient had a conventional digital screening mammogram. In the lower inner quadrant of the left breast, there is a possible focal asymmetry ( ▶ Fig. 62.3 and ▶ Fig. 62.4).


62.3 BI-RADS Classification and Action


Category 0: Mammography: Incomplete. Need additional imaging evaluation and/or prior mammograms for comparison.


62.4 Diagnostic Images


( ▶ Fig. 62.5, ▶ Fig. 62.6, ▶ Fig. 62.7)


62.4.1 Imaging Findings


The diagnostic imaging demonstrates a possible persistent asymmetry on the craniocaudal (CC) spot-compression mammogram ( ▶ Fig. 62.5). The mediolateral oblique (MLO) spot-compression ( ▶ Fig. 62.6) and medioateral (ML) mammograms ( ▶ Fig. 62.7) are less suggestive of a true asymmetry. The corresponding CC and MLO digital breast tomosynthesis (DBT) movies demonstrate that the focal asymmetry seen on screening mammography is a summation artifact created by overlapping tissues in the same imaging plane.


62.5 BI-RADS Classification and Action


Category 1: Negative


62.6 Differential Diagnosis




  1. Summation artifact (superimposition of breast tissue): The DBT movies obtained at the diagnostic evaluation best demonstrated that this asymmetry is created by overlapping tissue.



  2. Radial scar: Subtle asymmetries can represent a radial scar. The DBT images did not support any underlying architectural distortion or other suspicious findings.



  3. Carcinoma: Carcinomas can initially present as subtle findings, especially lobular carcinoma. It is reassuring that the DBT images revealed overlapping tissue.


62.7 Essential Facts




  • Many screening mammograms are recalled for summation artifacts.



  • DBT is designed to reduce the summation effects of overlapping tissues and improve lesion conspicuity.



  • DBT makes suspicious findings more apparent and helps the reader to recognize normal structures more clearly.



  • In DBT the reconstruction of the three-dimensional breast image into slices helps to uncover those areas of overlapping tissue.


62.8 Management and Digital Breast Tomosynthesis Principles




  • DBT has demonstrated a reduction in recall rate from 7 to 15% in clinical studies.



  • Improvements in sensitivity and specificity are seen on DBT irrespective of breast tissue density.



  • DBT is approved for screening and diagnostic mammography imaging. The role in breast imaging is evolving.



  • Drawbacks to DBT are the increased radiation for combination exams (FFDM and DBT) and the increased time for reading a study (reported as twice the time).



  • DBT produces extremely large data files that require extra PACS (picture archiving and communication system) storage capacity.


62.9 Further Reading


[1] Brandt KR, Craig DA, Hoskins TL, et al. Can digital breast tomosynthesis replace conventional diagnostic mammography views for screening recalls without calcifications? A comparison study in a simulated clinical setting. AJR Am J Roentgenol. 2013; 200(2): 291‐298 PubMed



978-1-62623-209-9_c062_f001.tif


Fig. 62.1 Left craniocaudal (LCC) mammogram.

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Apr 25, 2018 | Posted by in BREAST IMAGING | Comments Off on Possible Focal Asymmetry

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