Assessment of myocardial viability in rats: Evaluation of a new method using superparamagnetic iron oxide nanoparticles and Gd‐DOTA at high magnetic field

The aim of this study was to detect salvageable peri‐infarction myocardium by MRI in rats after infarction, using with a double contrast agent (CA) protocol at 7 Tesla. Intravascular superparamagnetic iron oxide (SPIO) nanoparticles and an extracellular paramagnetic CA (Gd‐DOTA) were used to characterize the peri‐infarction zone, which may recover function after reperfusion occurs. Infarcted areas measured from T1‐weighted (T1‐w) images post Gd‐DOTA administration were overestimated compared to histological TTC staining (52% ± 3% of LV surface area vs. 40% ± 3%, P = 0.03) or to T2‐w images post SPIO administration (41% ± 4%, P = 0.04), whereas areas measured from T2‐w images post SPIO administration were not significantly different from those measured histologically (P = 0.7). Viable and nonviable myocardium portions of ischemically injured myocardium were enhanced after diffusive Gd‐DOTA injection. The subsequent injection of vascular SPIO nanoparticles enables the discrimination of viable peri‐infarction regions by specifically altering the signal of the still‐vascularized myocardium. Magn Reson Med 52:932–936, 2004. © 2004 Wiley‐Liss, Inc.