Cardiovascular interventional MR imaging: a new road for therapy and repair in the heart.
Over the last 5 years, interventional MR imaging has been fertile ground for research. Real-time MR imaging, combined with recent advances in other MR imaging modalities such as perfusion imaging and intravascular imaging, has opened up new paths for cardiac therapy. The recent reports on cardiac stem cell therapy guided and monitored by MR imaging suggest that we are already seeing the establishment of an important role for cardiac MR imaging in cardiac restoration. The collaborative effort from a multidisciplinary team of basic biologists, engineers, and clinicians will refine stem cell incubation and labeling for MR-guided transcatheter endomyocardial injections, and this in turn may facilitate new studies in humans. Several groups have demonstrated in animal studies the feasibility of MR-guided catheter interventions for the treatment of congenital heart disease and arrythmia therapy. Hence, applications in humans remain the challenge for the next years. Although there have been first reports of cardiac catheterizations in humans by combined use of x-ray fluoroscopy and MR imaging, there are no reports in the literature suggesting that active tracking methods by MR imaging have been applied to humans. Safety issues (namely, heating of catheters and wires) hamper clinical use, particularly in infants and children. Current reports are promising that these limitations will be overcome in the near future and will eventually reduce x-ray usage during catheterization. In its current state, cardiac MR imaging offers a unique opportunity to investigate new therapeutic strategies for the treatment of congenital and acquired heart disease.