Influence of gadolinium-based contrast agent (GBCA) on the diffusion weightings of breast lesions: an intra-patient analysis.

purposeTo investigate the influence of gadolinium-based contrast agent (GBCA) administration on breast lesions' signal intensities on diffusion-weighted images and its derived ADC maps acquired 2 min after GBCA administration. MATERIALS AND

methodsAn intra-patient analysis was performed. 110 lesions > 5 mm in 93 patients, visible on screening and pre-operative MRI scans at 1.5 T and 3.0 T, were included. Pre-contrast and post-contrast DWI were acquired with single-shot spin-echo echo-planar imaging (SSh-SE-EPI) with b0, b50, b150, and b800 diffusion weightings. 2D regions of interest were drawn. Each b value was separately analyzed regarding signal intensities on DWI. Furthermore, ADC values were compared based on the pairs b0-b800 and b150-b800. The comparison between pre- and post-contrast DWIs was investigated within and between different groups (overall, malignant/benign, and at 1.5/3.0 T). The Wilcoxon-signed rank test and independent Student T test were used when appropriate. P < 0.01 was considered as statistically significant.

resultsOverall, and for malignant and benign lesions separately, a significant change after contrast administration in signal intensity was observed at each specific b value, irrespective of the use of 1.5 T or 3.0 T. The effect of contrast administration was overall notably different when comparing b0 (+ 9.4%) vs. b800 (+ 11.8%), but this was not observed between b150 (11.4%) and b800 (11.8%) (P = 0.10). In malignant lesions, specifically, all b value pairs, except b0-b50, showed significant differences in GBCA effects. This translates into a pre-post-contrast difference of the ADC value of 3.2% (P = 0.02) when based on b0-b800 and 0.9% (P = 0.11) when using b150-800.

conclusionsThere is a limited, but significant effect of contrast administration on DW signal intensities measured 2 min after contrast administration. This effect is not the same for each b value. Signal change is stronger for high than for low b values, which leads to a larger change in measured ADC values after contrast administration when b0 and b50 are incorporated in the calculation. As a consequence, ADC calculations obtained from b150-b800 seem to be more robust than those obtained from b0-b800.