Blood pool contrast agents for cardiovascular MR imaging

The distribution and elimination of contrast agents is mainly determined by their size. First-pass perfusion with the use of blood pool contrast agent s (BPCAs) and/or rapid clearance blood-pool-like contrast agents may allow quantitative myocardial perfusion evaluation in patients. This requires con trast bolus injection with a very fast injection speed, A major profit from BPCAs is expected for magnetic resonance angiography (MRA), The persistent signal-enhancing effects of BPCAs allow for a longer acquisition time wind ow, which may be used to increase both the signal-to-noise ratio and/or ima ge resolution, This is of paramount importance for coronary imaging, in whi ch high-resolution imaging is desired. Moreover, the improved acquisition t ime window can be used to make multiple scans after one contrast injection. The role of ultrasmall paramagnetic iron oxide particles (USPIOs) for MRA is not clear yet, as they are limited by T2* effects at higher doses, Sever al safety aspects have to be taken into account before BPCAs are applied in humans, for whom toxicity caused by the injection speed is a concern, (C) 1999 Wiley-Liss, Inc.