Effect of contrast agent on the results of in vivo 1H MRS of breast tumors - is it clinically significant?

Choline (Cho) signal identification and quantification in 1H MRS are used in breast cancer diagnosis. However, an influence of the gadolinium-based contrast agent on the Cho amplitude has been reported experimentally. This study aims to identify the impact of gadolinium-based contrast agents on Cho detection and quantification in postcontrast breast MRS. Consecutive patients were recruited prospectively and randomly allocated to two groups. Group A received a neutral (gadolinium diethylenetriaminepentaacetic acid bis-methylamide) and group B an ionic (gadolinium diethylenetriaminepentaacetic acid) contrast agent, each at a dosage of 0.1mmol/kg. First, the presence of Cho was identified visually. Then, the normalized Cho intensity in malignant lesions was quantified. Multivariate analysis was applied to identify independent influencing factors on Cho. Sixty-three lesions were investigated [A, n=34; B, n=29; 43 malignant (one bilaterally malignant), 20 benign]. Cho was identified visually in 14 of 20 malignant tumors in group A and 12 of 22 malignant tumors in group B (p=0.477). Normalized Cho differed significantly (p=0.001) between groups A (mean, 26.8 +/- 6.0AU) and B (mean, 18.2 +/- 12.5AU). No linewidth differences were identified (p>0.05). Multivariate analysis revealed only group membership (A versus B) as an independent predictor of Cho (p=0.017). The results suggest stronger negative effects of an ionic relative to a neutral gadolinium-based contrast agent on breast tumor MRS in vivo. These results should be considered when conducting and comparing quantitative Cho measurements in the breast. Copyright (c) 2011 John Wiley & Sons, Ltd.