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Using a one‐dimensional rapid imaging technique, we have found that injection of lanthanide chelates such as Gd(DTPA)²⁻ leads to a significant decrease (50%) in rat brain signal intensity at 1.45 T using T₂‐weighted pulse sequences; however, no effect of comparable size is observed with T₁‐weighted pulse sequences. The transient effect and its kinetics were followed with a temporal resolution of between 1 and 8 s. Experiments with different lanthanide chelates show that the observed decrease in signal intensity correlates with the magnetic moment of each agent but not with their longitudinal relaxivity. Three‐dimensional chemical‐shift resolved experiments demonstrate significant line broadening in brain during infusion with Dy(DTPA)²⁻ Our results show that the cause of this effect is the difference in susceptibility between the capillaries, containing the contrast agent, and the surrounding tissue. As a result …