Baseline T1 Signal Intensity:
BSI varied considerably across individuals with a mean of 167.73 ± 49.16 (standard deviation) and 175.86 ± 48.85 in the right and left breast,
respectively.
The initial mean difference in BSI of 8.14 was statistically significant,
based on a paired t-test (p<0.001).
BSI increased linearly with age,
body weight,
and BMI (Figure 1,
2 and 3).
BSI decreased linearly with body height,
but this association was weaker and showed no significance (p=0.38).
Age,
body weight,
and BMI effects were higher in postmenopausal women compared to premenopausal women as well (p<0.01).
Postmenopausal status was associated with a significantly higher BSI in the single model but this effect ceased to be of relevance when including age in the full model (p=0.26).
Modeling Contrast Enhancement after Injection of Gadobutrol:
CE time courses,
displayed separately for the right and left breast in Figure 4,
showed a monotonous increase in SI over time that gradually leveled off.
Because the time courses were similar in both breasts,
we modeled the mean CE across both breasts in all further analyses.
Mean RCE was 8.07%,
13.78%,
18.23%,
22.14%,
and 24.56% at 1,
2,
3,
4,
and 5 min,
respectively.
However,
RCE varied strongly across individuals (Figure 5).
Influence of Anthropometric Measures and Menopausal Status:
CE increased significantly with body weight (p<0.01,
Figure 6).
Additionally,
women with higher BSI tended to have a higher CE slope.
Age had minor effects on the time course when including menopausal status (p=0.68) and also within the strata of pre- and postmenopausal women (p=0.54).
CE of normal breast parenchyma was approximately 30% higher in premenopausal than in postmenopausal women (p< 0.001,
Figure 7). Mean CE was 6.07%,
10.72%,
14.88%,
18.27%,
and 20.27% in postmenopausal women and 11.51,
19.83,
25.54,
30.13,
and 33.74 in premenopausal women at 1,
2,
3,
4,
and 5 min after contrast,
respectively.
Influence of Postmenopausal Hormone Therapy and Oral Contraceptives:
Before menopause,
CE decreased significantly in OC users compared to non-OC users (p< 0.01,
Figure 8).
The largest change was observed between baseline and the first minute after contrast medium injection.
After menopause,
enhancement was similar in HT users and non-HT users (p= 0.94,
Figure 8).