Purpose
To determine whether apparent diffusion coefficient (ADC) measures of breast
lesions at 3 tesla (T) are affected by gadolinium administration.
Materials and Methods
The study included 19 patients who underwent 3T MRI. Diffusion-weighted imaging
(DWI) was acquired with b=0, 100, and 800 s/mm2 before and after a dynamic
contrast-enhanced (DCE) sequence. ADC values were measured for each lesion and normal
fibroglandular tissue. Pre and post-contrast ADC measures were compared by Wilcoxon
signed-rank test, and differences between groups were compared by Mann-Whitney U test;
p<0.05 was considered statistically significant.
Results
There was no significant difference in pre and post-contrast ADC measured at
b=0,100,800 s/mm2 for malignancies (median change:
−0.4%,−0.01×10−3 mm2/s,
p=0.40), but there was a slight increase in post-contrast ADC in normal tissue
(+1.6%,+0.04×10−3 mm2/s, p=0.0006).
Findings were similar for both lesions
(−0.4%,−0.01×10−3 mm2/s,
p=0.54) and normal tissue (+1.5%,+0.03×10−3
mm2/s, p=0.002) with ADC measured at b=0,800 and also at b=100,800
s/mm2 (lesions: +0.9%,+0.01×10−3
mm2/s, p=0.71; normal tissue:
+1.8%,+0.03×10−3 mm2/s, p=0.005). For
lesions, results were not affected by lesion size, type (mass vs. non-mass enhancement),
mean initial enhancement, late enhancement, or delayed enhancement rate on DCE-MRI
(p>0.05 for all). Normal tissue showed some trends with greater progressive
enhancement rates and higher late enhancement levels correlating with greater increase
in post-contrast ADC (p=0.09 for both).
Conclusions
Our results show that breast lesion ADC measures using our approach were not
significantly altered following DCE-MRI at 3T, suggesting DWI and DCE-MRI can be
performed in any order without affecting diagnostic criteria. However, influences of
contrast on ADC measures in normal breast tissue were observed and require further
investigation.
