Table 3.
Associationa of density estimates (percent density, dense area, and non-dense area) and categoriesb of the four acquisition parameters
| Spearman correlation coefficient(P value) | Category 1 | Category 2 | Category 3 | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 22-25 | 26-27 | 28-32 | ||||||||
|
Cases (n = 254)c |
Subcohort (n = 1,910)c |
Mean | SD | Mean | SD | Mean | SD | |||
| Percent density | 0.09 (0.15)d | 0.04 (0.07)d | 17.1 | 13.8 | 17.3 | 14.8 | 19.0 | 14.3 | ||
| Dense area | 0.28 (< 0.001)d | 0.16 (< 0.001)d | 2,070 | 1,603 | 2,404 | 1,864 | 2,987 | 2,238 | ||
| Non-dense area | 0.20 (0.002)d | 0.16 (< 0.001)d | 12,349 | 6,393 | 14,386 | 7,512 | 15,405 | 8,289 | ||
| Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 | |||||||
| mAs | 9-126 | 127-173 | 174-194 | 194-371 | ||||||
| Mean | SD | Mean | SD | Mean | SD | Mean | SD | |||
| Percent density | -0.03 (0.60) | -0.06 (0.008) | 18.4 | 14.3 | 18.4 | 14.9 | 17.1 | 13.9 | 16.3 | 13.3 |
| Dense area | 0.14 (0.02) | 0.09 (< 0.001) | 1,958 | 1,481 | 2,432 | 1,843 | 2,415 | 1,867 | 2,534 | 2,086 |
| Non-dense area | 0.24 (< 0.001) | 0.25 (< 0.001) | 10,906 | 6,034 | 13,412 | 7,284 | 14,214 | 7,091 | 15,404 | 7,571 |
| Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 | |||||||
| Thickness, mm | 6-45 | 46-54 | 55-62 | 62-94 | ||||||
| Percent density | -0.25 (< 0.001) | -0.27 (< 0.001) | 23.3 | 16.5 | 17.7 | 13.2 | 15.7 | 12.7 | 13.0 | 11.3 |
| Dense area | -0.01 (0.89) | -0.12 (< 0.001) | 2,512 | 1,846 | 2,425 | 1,857 | 2,261 | 1,798 | 2,113 | 1,844 |
| Non-dense area | 0.41 (< 0.001) | 0.35 (< 0.001) | 10,211 | 6,210 | 13,604 | 7,142 | 14,152 | 6,632 | 16,236 | 7,494 |
| Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 | |||||||
| Compression force, pounds | 6.6-21 | 22-24 | 25-28 | 28-49 | ||||||
| Percent density | -0.14 (0.02) | -0.16 (< 0.001) | 20.5 | 15.1 | 18 | 14.5 | 16.9 | 14.1 | 14.2 | 11.6 |
| Dense area | -0.01 (0.88) | -0.02 (0.39) | 2,360 | 1,761 | 2,258 | 1,695 | 2,407 | 1,999 | 2,283 | 1,880 |
| Non-dense area | 0.26 (< 0.001) | 0.31 (< 0.001) | 10,859 | 5,945 | 12,788 | 6,749 | 14,153 | 6,759 | 16,536 | 8,160 |
aMean and SD of density by categories are estimated using the subcohort only. Correlation coefficients estimated on cases and subcohort separately. bQuartiles were used where appropriate. The distribution of voltage peak (kVp) was highly skewed and was categorized into three levels. cOwing to missing acquisition parameters, 18 cases and 47 controls that were included in the analyses depicted in Table 2 are not included here. dCorrelation coefficients for kVp are based on the three categories and not continuous measures. mAs, milliampere-seconds; SD, standard deviation.