Manganese-based agents can be infused intravenously or be administered orally. Compared with other ions, manganese is selectively taken up by the hepatocytes and excreted via the bile (Fig. 1). The uptake is correlated with the mitochondrial function and is thus a sign of the oxygenation of the hepatocyte. After infusion, manganese can be seen in the pancreas, adrenal glands and the pituitary, but not after oral intake, which also opacifies the bowel content. Manganese is a relatively non-toxic ion, but in high doses it may be toxic; it may accumulate, for example, in the brain, where it may cause degenerative lesions with Parkinsonism as a result. Therefore, manganese may not be administered in high doses into a peripheral vein. A normal liver removes 80 to 90% of the manganese during a single passage. Manganese-based contrast agents for signal-enhanced lumen filling of the gastrointestinal tract have also been on the market. For the time being, manganese-based contrast media are no longer marketed in most countries.

FIGURE 1 (A, B) MRI of the upper abdomen before and after administration of manganese. Only the signal from the liver is increased.

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