Gadolinium-Based Contrast Agents for Breast MRI and Uncertainties About Brain Gadolinium Retention

Gadolinium-based contrast agents (GBCAs) available for magnetic resonance imaging (MRI) of the breast cause tissue signal changes that influence not only the diagnostic performance of contrast-enhanced protocols but also the expected findings on diffusion-weighted imaging (DWI) or 1H magnetic resonance spectroscopy. The high-risk screening setting, potentially necessitating repeated examinations over decades, requires that a specific evaluation of the risk-benefit balance in which the diagnostic performance achieved with a given GBCA is balanced against the risk of acute and late adverse reactions. The incidence of acute adverse reactions to GBCAs is relatively low, approximately three- to fivefold less than that of iodinated contrast agents used for x-ray-based imaging. Tangible late adverse effects include nephrogenic systemic fibrosis (NSF) which is a real disease associated with administration of GBCAs to patients with severe chronic (Stage 4 or 5) or acute kidney disease. However, the introduction of renal function testing before GBCA administration, combined with GBCA dose limitation to a standard 0.1 mmol/kg body weight and contraindication of GBCAs mostly associated with NSF, appears to have resulted in the elimination of NSF as worldwide GBCA-related disease. A second phenomenon associated with GBCA administration is gadolinium (Gd) retention in human tissues, including the brain (evidences in favor of a dynamic process made the use of the wording Gd retention more appropriate than Gd deposition). Although no harm to patients or any adverse clinical effects have yet been associated with Gd retention, the comparatively recent observation of this phenomenon necessitates its consideration in any evaluation of GBCA risk-benefit balance. To perform an accurate risk-benefit assessment, breast radiologists should be aware of the differences among the available GBCA molecules in terms of diagnostic performance and possible association with tissue Gd retention. In our opinion, for high-risk women, the balance is in favor of continuing the use of yearly contrast-enhanced MRI screening using macrocyclic GBCAs. Interesting future research directions are those concerning contrast dose reduction and non-contrast DWI-based protocols for breast MRI screening.