Abstract
Background: The latest generation of interactive cardiac magnetic resonance (MR) scanners has made cardiac interventions with real-time MRI possible. To date, cardiac MRI has been mostly applied to measure myocardial perfusion, viability, and regional function, but now the application of cardiac MRI can be extended to cardiovascular interventions. The purpose of this article is to illustrate the potential of MRI in stem cell therapy for cardiac restoration. Methods: We have applied MRI to (1) interactively target myocardial injections with a novel stem cell delivery catheter, and to compare gadolinium/blue dye injections to pathology; (2) assess myocardial perfusion with MR first pass imaging in an infarct model treated with stem cell therapy versus control animals; (3) measure regional functional changes using myocardial tissue tagging in the same animals. Results: We were able to demonstrate the feasibility and safety of myocardial injections under MR fluoroscopy. The intramyocardial distribution of the blue dye at necropsy correlated well with the extent of gadolinium, as detected with a three-dimensional inversion recovery MR pulse sequence for late enhancement immediately after contrast injection. Preliminary results show that myocardial perfusion reserve and regional wall motion improved in the stem-cell-treated group, compared to a control group. Conclusions: These preliminary results suggest that (1) injections into the LV myocardium can be performed under real-time MRI guidance using a directed catheter approach, and (2) regional myocardial perfusion and function, measured with MRI, both improve after stem cell therapy. This ongoing study demonstrates the potential of MRI for image-guided interventions, combined with detailed evaluation of anatomy, function, perfusion, and viability.