Purpose
Breast density is important in the evaluation of breast cancer risk. At present, breast density is evaluated using two‐dimensional projections from mammography with or without tomosynthesis using either (a) subjective assessment or (b) a computer‐aided approach. The purpose of this work is twofold: (a) to establish an algorithm for quantitative assessment of breast density using quantitative three‐dimensional transmission ultrasound imaging; and (b) to determine how these quantitative assessments compare with both subjective and objective mammographic assessments of breast density.
Methods
We described and verified a threshold‐based segmentation algorithm to give a quantitative breast density (
QBD
) on ultrasound tomography images of phantoms of known geometric forms. We also used the algorithm and transmission ultrasound tomography to quantitatively determine breast density by separating fibroglandular tissue from fat and skin, based on imaged, quantitative tissue characteristics, and compared the quantitative tomography segmentation results with subjective and objective mammographic assessments.
Results
Quantitative breast density (
QBD
) measured in phantoms demonstrates high quantitative accuracy with respect to geometric volumes with average difference of less than 0.1% of the total phantom volumes. There is a strong correlation between QBD and both subjective mammographic assessments of Breast Imaging ‐ Reporting and Data System (
BI
‐
RADS
) breast composition categories and Volpara density scores — the Spearman correlation coefficients for the two comparisons were calculated to be 0.90 (95%
CI
: 0.71–0.96) and 0.96 (95%
CI
: 0.92–0.98), respectively.
Conclusions
The calculation of breast density using ultrasound tomography and the described segmentation algorithm is quantitatively accurate in phantoms and highly correlated with both subjective and Food and Drug Administration (
FDA
)‐cleared objective assessments of breast density.
Elevated breast density is among the strongest independent predictors of breast cancer. Breast density scores are critical inputs in models used to calculate a patient's lifetime risk of developing breast cancer. Today, the only FDA-cleared technology for assessing breast density uses mammography. An alternative modality for breast density quantification is 3D transmission ultrasound (TU). In this retrospective study, we compared automated breast density calculations derived from TU using quantitative breast density (QBD) and mammography with tomosynthesis using VolparaDensity 3.1 for 225 breasts. Pearson correlation coefficients (r) and intraclass correlation coefficients were compared. Subset analyses of extremely dense breasts, premenopausal, and postmenopausal breasts were also performed. Comparative analysis between radiologist-derived density assessment and objective automated scores was performed. Calculations from TU and mammography with tomosynthesis for breast density, total breast volume (TBV), and fibroglandular volume (FGV) were strongly correlated (r ¼ 0.91, 0.92, and 0.67, respectively). We observed moderate absolute agreement for FGV and breast density, and strong absolute agreement for TBV. A subset of 56 extremely dense breasts showed similar trends, however with lower breast density agreement in the subset than in the full study. No significant difference existed in density correlation between premenopausal and postmenopausal breasts across modalities. QBD calculations from TU were strongly correlated with breast density scores from VolparaDensity. TU systematically measured higher FGV and breast density compared with mammography, and the difference increased with breast density.Impact: TU of the breast can accurately quantify breast density comparable with mammography with tomosynthesis.
Quantitative high resolution (QHR) images of speed of sound and attenuation in human breast have been made using full wave inverse scattering in three-dimension (FWIS3D), where only soft tissue is present. The FWIS3D technology and method are reviewed. Recent QHR images in the presence of bone and gas have been obtained with FWIS3D and are shown. Transmission mode quantitative and refraction corrected reflection images of small piglet abdomen, thorax, and head are shown. QHR images of the human knee using the same technology are shown. Human Knee is difficult due to the predominant presence of bone. With low frequency FWIS3D, the meniscus, structure within the Femur-Tibia (F-T) space, ligaments, and the infrapatellar fat pad can be seen. The intra-condyle space in the Femur is visible. It was earlier established that 3D modelling was necessary for breast. It is shown to be even more important for F-T space and whole body imaging. Quantitative estimates of high speed early development bone are made, and imaging through neo-natal skull is performed. Clear correspondence with known structures even in the presence of gas is displayed. This reveals FWIS3D ultrasound tomography as a 21st century whole body imaging modality.
Patient preferences for breast imaging care and location vary and are correlated with specific demographic characteristics. An understanding of these population characteristics can shape organizational strategies for improving patient-centered care and outcomes.
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