Table S1. Cross-Tabulation of Breast Density Categories Assessed by US and Mammography

US Density Category
1 / 2 / 3 / 4 / Total
Mammographic
Density Category / 1 / 25
(8.2%) / 6
(2.0%) / 0 / 0 / 31
(10.2%)
2 / 5
(1.6%) / 52
(17.1%) / 13
(4.3%) / 3
(1.0%) / 73
(24.0%)
3 / 0 / 27
(8.9%) / 102
(33.6%) / 28
(9.2%) / 157
(51.6%)
4 / 0 / 0 / 11
(3.6%) / 32
(10.5%) / 43
(14.1%)
Total / 30
(9.9%) / 85
(28.0%) / 126
(41.4%) / 63
(20.7%) / 304
(100%)

Table S1. Cross-Tabulation of Breast Density Categories Assessed by US and Mammography

with Exclusion of the Three Patients with One Breast

Note. – US assessment of breast density was performed using 4 categories based on the proportion of the breast occupied by fibroglandular tissue. Mammographic assessment was performed according to BI-RADS categories. Boldface numbers reflect the proportions of exact agreement between US and mammographic assessments for of breast density.

Table S2. Intermodality Agreement Values between US and Mammographic Assessments of Breast Density by Individual Radiologists with Exclusion of the Three Patients with One Breast

Radiologists / Percent Agreement (%) / к Value / ICC
Radiologist 1 / 74 / 0.70
(0.53 – 0.87) / 0.81
(0.67 – 0.90)
Radiologist 2 / 68 / 0.65
(0.46 – 0.83) / 0.79
(0.63 – 0.88)
Radiologist 3 / 61 / 0.62
(0.45 – 0.80) / 0.77
(0.61 – 0.87)
Radiologist 4 / 71 / 0.66
(0.49 – 0.84) / 0.78
(0.62 – 0.88)
Radiologist 5 / 74 / 0.70
(0.53 – 0.87) / 0.81
(0.66 – 0.90)
Radiologist 6 / 66 / 0.63
(0.46 – 0.80) / 0.77
(0.61 – 0.88)
Radiologist 7 / 74 / 0.63
(0.41 – 0.85) / 0.68
(0.46 – 0.82)
Radiologist 8 / 68 / 0.65
(0.47 – 0.83) / 0.78
(0.62 – 0.88)

Note. – Numbers in parentheses are the 95% confidence intervals. ICC = Intraclass Coefficient