Relating Dose of Contrast Media Administered to Uptake and Washout of Malignant Lesions on DCEMRI of the Breast

Rationale and Objectives

To quantify the relationship between dose of contrast administered and contrast kinetics of malignant breast lesions.

Materials and Methods

A total of 108 patients with 120 malignant lesions were selected for an institutional review board–approved review. Dynamic magnetic resonance protocol: one pre- and three or five post-contrast (at a fixed volume of 20 mL of 0.5 M gadodiamide) images. Patients were stratified into groups based on dose of contrast administered, after calculation of body weight (kg): Dose Group 1, <0.122 mmol/kg; Dose Group 2, 0.123–0.155 mmol/kg; Dose Group, 3 > 0.155 mmol/kg. Analysis of kinetic curve shape was made according to the Breast Imaging Reporting and Data System lexicon. Several quantitative parameters were calculated including initial and peak enhancement percentage (E₁ and E_peak). Linear regression was used to model the variation of kinetic parameters with dose.

Results

There was no difference found in the qualitative Breast Imaging Reporting and Data System descriptors of curve shape between the three dose groups. There was a trend for E₁ and E_peak to increase from Dose Group 1 to Dose Group 3 in malignant lesions overall, as well as in invasive ductal carcinoma lesions separately. Each decrement/increment of 0.05 mmol/kg in dose yielded a decrease/increase of 78% and 97% in E₁ for in situ and invasive cancers, respectively.

Conclusion

Contrast should be administered at fixed dose to achieve comparable levels of lesion uptake in women of different weights. Our results suggest that reducing the contrast administered to 0.05 mmol/kg, as has been suggested for patients at risk of developing nephrogenic systemic fibrosis, could substantially decrease the observed initial enhancement in some cancers.

Key Words: Breast MRI, contrast dose, kinetics, breast cancer