Abstract:
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Purpose: The local environment of delivered mesenchymal stem cells (MSCs) may affect their ultimate phenotype. Magnetic resonance fluoroscopy has the potential to guide intramyocardial MSC injection to desirable targets, such as the border between infarcted and normal tissue. We test the ability to: 1) identify infarcts, 2) to navigate injection catheters to pre-selected targets, 3) to inject safely even into fresh infarcts and 4) to confirm injection success immediately.
Methods and Materials: A 1.5 T MRI scanner was customized for interventional use, with rapid imaging, independent color-highlighting of catheter channels, multiple-slice 3D rendering, catheter-only viewing mode, and infarct-enhanced imaging. MRI receiver coils were incorporated into guiding catheters and injection needles. These devices were tested for heating and used for targeted MSC delivery. In ten infarcted pigs, myocardium was targeted using MR-Fluoroscopy. Real-time infarct-enhanced imaging included both saturation preparation steady-state free precession (sat-RT-SSFP) after intravenous gadolinium, and wall motion. Porcine MSCs were MRI-labeled with iron-fluorescent particles (IFP).
Results: Myocardial infarctions and their borders were clearly identifiable under MR-Fluoroscopy by patterns of myocardial contraction. Approximately 15 minutes after gadolinium injection, delayed hyperenhancement increased the contrast between normal and infarcted myocardium to enable targeting for up to 120 minutes with sat-RT-SSFP. Catheter navigation and a total of 34 cell injections were performed entirely with MR-Fluoroscopy at 8 frames/s with 1.7x3.3x8mm voxels. All 34 injections were safely and successfully delivered to their preselected targets, including infarct borders. IFP-labeled MSCs were readily visible upon delivery in vivo and post-mortem.
Conclusion: Precise targeted delivery of potentially regenerative cellular treatments to recent myocardial infarction borders is feasible using a magnetic resonance catheter delivery system. Magnetic resonance fluoroscopy permits visualization of catheter navigation, myocardial function, infarct borders, and labeled cells after injection.
Questions about this event email: dicka@nhlbi.nih.gov
Dick MD, A,
Magnetic Resonance Fluoroscopy Enables Targeted Delivery of Stem Cells to Infarct Borders in Swine. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3105197.html
