Diffusion-weighted imaging: Effects of intravascular contrast agents on apparent diffusion coefficient measures of breast malignancies at 3 Tesla.

Abstract

To determine whether apparent diffusion coefficient (ADC) measures of breast lesions at 3 Tesla (T) are affected by gadolinium administration. The study included 19 patients who underwent 3T MRI. Diffusion-weighted imaging (DWI) was acquired with b = 0, 100, and 800 s/mm(2) before and after a dynamic contrast-enhanced (DCE) sequence. ADC values were measured for each lesion and normal fibroglandular tissue. Pre- and postcontrast 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. There was no significant difference in pre- and postcontrast ADC measured at b = 0, 100, 800 s/mm(2) for malignancies (median change: -0.4%, -0.01 × 10(-3) mm(2) /s, P = 0.40), but there was a slight increase in postcontrast ADC in normal tissue (+1.6%, +0.04 × 10(-3) mm(2) /s, P = 0.0006). Findings were similar for both lesions (-0.4%, -0.01 × 10(-3) mm(2) /s, P = 0.54) and normal tissue (+1.5%, +0.03 × 10(-3) mm(2) /s, P = 0.002) with ADC measured at b = 0,800 and also at b = 100, 800 s/mm(2) (lesions: +0.9%, +0.01 × 10(-3) mm(2) /s, P = 0.71; normal tissue: +1.8%, +0.03 × 10(-3) mm(2) /s, P = 0.005). For lesions, results were not affected by lesion size, type (mass versus nonmass 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 postcontrast ADC (P = 0.09 for both). 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.