Metabolic and structural adaptations after acute myocardial infarction as assessed with multimodal CMR
Medical Physics, Biomedical Technology
Final Report Abstract
Cardiac magnetic resonance imaging (CMR) is able to visualize and quantify metabolic and structural alterations of the heart. During the DFG Research Fellowship “Metabolic and structural adaptations after acute myocardial infarction as assessed with multimodal CMR” the applicant Dr. Mareike Gastl and her collaborators were able to optimize CMR sequences for the detection of myocardial metabolites with regard to a better applicability in clinical settings, especially in acute myocardial infarction (AMI). The different pathways of myocardial metabolism to generate adenosine triphosphate were examined using two different CMR sequences. In a first approach, Creatine as the endpoint of the aerobic metabolism of triglycerides and glucose was examined using Creatine Chemical Exchange Saturation Transfer (CrCEST). Phantom and primary in vivo studies could show that the application of CrCEST and the quantification of the CEST signal is highly dependent on physiologic parameters such as pH, temperature as well as T 1 and T2 relaxation parameters. Small variations can already result in a marked reduction of the signal. Once implement for in vivo studies, a measurement of Cr could be of additional value in clinical settings for the estimation of myocardial energy states, e.g. in infarcted areas. As myocardial triglycerides are the major source for energy supply, 1H-MRS to quantify myocardial TG and CR, was optimized in a second approach with regard to clinical applicability. In this context, the sequence was improved in scan time, dependence on motion states, size of the region of interest and applicability after contrast agent in the gap between administration and late gadolinium enhancement. In a first clinical study, the sequence was applied in patients with cardiac amyloidosis and myocardial thickening. Myocardial thickening facilitates acquisition of spectra by choosing a reasonable size for the regions of interest thereby improving signal quality. It could be shown that myocardial triglyceride-to-water ratios were reduced in patients with amyloidosis whereas creatine was preserved. In first trials at the end of the funding period, 1H-MRS using smaller voxel sizes could successfully be acquired in remote and ischemic segments of patients with AMI. In addition, the applicant received dedicated training in CMR and was able to perform clinical studies about changes in myocardial functional (strain) and structural parameters (T2*) of different types of cardiovascular diseases (hypertrophic cardiomyopathy, coronary artery disease). The acquired skills and knowledge shall now be transferred to the science network of the University Düsseldorf with regard to metabolic imaging in myocardial infarction, e.g. as part of the STEMI registry and the Collaborative Research Centre (CRC 1116). This includes follow-up projects and further cooperation with the Institute for Biomedical Engineering, the University Heart Center of the University Hospital Zürich and the Institute of Diagnostic and Interventional Radiology, University Hospital Zürich.
