AbstractThe purpose of the study was to determine if derivatization of cholesterol with a paramagnetic label could result in an organ‐specific contrast agent for magnetic resonance imaging of the adrenal glands. Gadolinium‐DO3A‐labeled cholesterol was synthesized and the relaxivities in water and blood plasma determined at 0.47 T and 40°C. Organ distribution was measured at 2 (n= 2) and 24 (n= 2) hours after intravenous injection of a 50 μmol/kg dose of Gd‐DO3A‐cholesterol in rats weighing 220–240 g. T1‐weighted spin‐echo images were acquired at 2 T before and after injection of 50 μmol/kg Gd‐DO3A‐cholesterol (n= 2) and Gd‐DTPA (diethylenetriaminepentaacetic acid)‐albumin (n= 2). More than 99% of the Gd‐DO3A‐cholesterol was found to be protein bound in bovine serum. High T1 and T2 relaxivities were found in water and plasma. High tissue concentrations of Gd‐DO3A‐cholesterol were found only in adrenal glands and liver. At 24 hours, adrenal gadolinium concentrations were about 10 times higher than in blood. At 2 hours after injection of Gd‐DO3A‐cholesterol. enhancement was 162% in adrenal glands and 146% in liver. With Gd‐DTPA‐albumin, enhance