Intra-Arterial Spin Labeling with Catheter-based Coils for Myocardial Perfusion Quantification

• Applicant: Dr. Simon Reiss
• Subject Area: Medical Physics, Biomedical Technology ; Cardiology, Angiology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 494790146

Magnetic resonance imaging (MRI) plays an emerging role in the guidance of cardiovascular interventions. MRI provides an excellent soft tissue contrast as well as quantitative imaging methods that are not available with conventional X-ray fluoroscopy; in particular, MRI-based first-pass perfusion measurements might be highly valuable for the detection and quantification of ischemic tissue in the myocardium. So far, MR-guided percutaneous coronary interventions (PCI) for the treatment of ischemic heart disease have only been performed in large animals. The clinical value of MR-guided PCI may strongly be enhanced if imaging methods would be available that quantify myocardial perfusion in segments supplied by the culprit vessel. With such a technique the extent of myocardial ischemia could be quantified and the success of the intervention could be validated already during the intervention. However, the conventional MRI perfusion measurement use gadolinium (Gd)-based contrast agents which are contraindicated in patients with impaired kidney function, and can lead to accumulation of Gd in the brain. Furthermore, the relatively long half-life of Gd-based contrast agents in scar or fibrous tissue leads to unwanted tissue contrast changes which last for the total duration of the intervention.In this proposal, a novel method will be developed that replaces exogenous contrast agents with intra-arterial spin labeling (iASL) for quantitative myocardial perfusion measurements during MR-guided catheterization. A prerequisite for successful MR-guided PCI is the active visualization of the catheter tip, which is often achieved with local radiofrequency (RF) receive coils. In this project RF coils will be designed that enable both the visualization of the catheter tip and efficient arterial spin labeling of the blood flowing past the catheter. With a numerical simulation framework the labeling effect of varying coil designs will be modeled and optimized under coronary flow conditions. Prototypes of catheters will be built and tested in realistic phantoms of myocardial perfusion. Moreover, optimal pulse sequences will be developed that efficiently use the separate catheter coil for continuous spin labeling of the coronary blood. Finally, a post-processing pipeline will be set up that calculates and displays perfusion maps acquired with the proposed iASL method in real-time. Ultimately, catheter-based iASL is envisioned to provide an efficient perfusion measurement technique that strongly increases the value of MR-guided PCI while avoiding the risks of contrast agent-based perfusion measurements.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Michael Bock