Contrast enhancement of manganese-hydroxypropyl-tetraacetic acid, an MR contrast agent with potential for detecting differences in myocardial blood flow

Purpose To determine whether the contrast agent MnHPTA has potential for detecting differences in myocardial blood flow. Materials and Methods R1 in the myocardium was calculated from MR signal intensity measurements in 18 pigs after intravenous injection of 5, 15, or 25 μmol MnHPTA/kg body weight. Measurements were made in each animal after administration at rest and during dobutamine‐induced stress. Results A difference of approximately 0.1 sec−1 in the R1 increase between rest and stress still remained 31 minutes after administration of 25 μmol MnHPTA/kg body weight. When two consecutive MnHPTA injections were performed, the second injection induced a lower R1 increase than the corresponding first injection. Conclusion MnHPTA at a dose of 25 μmol/kg body weight (b.w.) has the potential to detect perfusion differences in myocardium. When two consecutive injections of MnHPTA were administered, the R1 change after the second injection was affected by the earlier administration. Therefore, a protocol including more than one administration is not ideal for this contrast agent. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.