6th International Workshop on Breast Densitometry and Breast ...

6 th <strong>International</strong> <strong>Workshop</strong> on Breast Densitometry
and Breast Cancer Risk Assessment
P3 COMPARISON OF CUMULUS AREA DENSITY WITH TWO AUTOMATED
VOLUMETRIC BREAST DENSITY ALGORITHMS
Olivier Alonzo-Proulx 1 , Martin Yaffe 1 , Jennifer Harvey 2 .
1 Sunnybrook Health Sciences Centre, 2075 Bayview Ave., Toronto, Ontario Canada, M4N 3M5;
2 University of Virginia Health System, Charlottesville, Virginia
Purpose: Measurements of breast density made with the Cumulus interactive threshold algorithm have
been shown to be moderately associated with breast cancer risk. In this work we compare two volumetric
density (VBD) measures (the volume proportion of fibroglandular tissue), with Cumulus area percent
density (PD) to validate the volumetric algorithms.
ABSTRACTS
Methods and materials: 310 women who had both film-screen (FS) and digital mammograms as part of
the ACRIN DMIST were analyzed for PD (left CC, FS) and VBD (left and right CC, digital). One VBD
algorithm, ‘Cumulus Volume’ is based on a prior calibration of the imaging signal versus tissue thickness
and composition. The second algorithm, ‘Volpara’, finds a pixel where only fatty tissue is present, whose
signal intensity is then used as a reference to determine the density on the image. PD and both VBD
values were compared, and density color maps were visually reviewed. The relation between the VBD of
the left-right pairs was investigated, as well as the relation between the two volumetric algorithms.
Results: The correlation between Cumulus PD with Cumulus VBD and Volpara VBD yielded good
results (R 2 correlation of 0.74 and 0.76 respectively, using a 2 nd order polynomial fit). Outliers between
Cumulus PD and Cumulus VBD were due to thin breasts, which have a higher volume density because of
the skin contribution, to thick breasts where the thickness estimation was erroneous, or from poorly
exposed images. Outliers between Cumulus PD and Volpara VBD were due to the algorithm being unable
to find an adequate reference fatty pixel on dense breasts. The linear correlation between Volpara and
Cumulus VBD was very good (R 2 =0.82), and Volpara VBD overall had lower values since it excludes the
effect of skin in the volume density. The linear correlation between the left and right breast using
Cumulus VBD was excellent (R 2 =0.94).
Conclusion: Values obtained using either volumetric algorithms showed good correlation to the area
method, with only a few outliers, indicating that VBD can potentially be used in breast cancer risk
models. The algorithms were strongly correlated with each other. The left and right Cumulus VBD were
very strongly correlated, an indication of the algorithm’s reliability.
Clinical relevance: Volumetric breast density measurements are automated, perfectly reproducible,
correlate well with standard area density methods, and can thus be used to develop breast cancer risk
models.
Figure:
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