USE OF SUPERPARAMAGNETIC CONTRAST-MEDIA TO SUPPRESS SIGNAL FROM FLOWING SPINS - PRELIMINARY EXPERIENCE

The authors describe their preliminary experience with the use of supe rparamagnetic magnetic resonance (MR) imaging contrast media for suppr ession of signal from flowing blood. The goal of this work was to dete rmine if a superparamagnetic contrast agent could successfully elimina te blood signal during cardiac-gated MR imaging, thereby eliminating o r reducing flow artifacts associated with the complex and variable hem odynamics within the heart chambers. Imaging and data analysis were pe rformed in 17 dogs subjected to experimental myocardial infarction as part of a parallel project. Six doses (0.2, 1, 2, 3.5, 4, 5, and 10 mg /kg) of AMI-25, an experimental contrast agent, were used in the study . Spin-echo imaging was performed immediately before and every 5 minut es (for an average of 25 minutes) after bolus injection of the contras t agent. Variations in the image signal-to-noise ratio relative to a b aseline (before injection of contrast agent) image were assessed as a function of dose and time. Preliminary results suggest that a consider able reduction in blood flow artifacts and, hence, increases in image signal-to-noise ratio can be achieved at doses greater than or equal t o 3.5 mg/kg, for approximately 20 minutes after injection. Doses equal to or less than 2 mg/kg and images obtained more than 20 minutes afte r injection (regardless of dose) did not reliably show hemodynamic art ifact suppression.