T1 Map of Post-Myocardial Infarction for Precise Tissue Characterization
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Cardiac magnetic resonance (CMR) imaging generates exquisite tissue contrast to characterize the myocardium based on the proton density and magnetization properties. A wide range of CMR imaging sequences enables precise imaging of the function and morphology of the heart, using myocardial-specific T1 and T2 relaxation times. The ability of longitudinal relaxation time or T1 holds the potential to translate the tissue-specific property1 into personalized predictive diagnostics. T1 measurement reflects the individual exponential time constant needed for 63% of the tissue magnetization to realign with the external magnetic field and become active again. Therefore, the shorter the T1, there are more protons available for imaging over the same period with brighter signal. Tissue edema, a well-known cardinal sign of inflammation and tissue injury, lengthens the myocardial native T1 while shortens the postcontrast T1.2 Using novel CMR pulse sequences, it is possible to quantify the T1 value as it is encoded within each voxel.3 T1 values are then colored mapped to simplify visual interpretation.4 T1 mapping has been used successfully to characterize normal myocardium,5 nonischemic cardiomyopathy,6 and acute and chronic myocardial infarction (MI).7 In addition, the gadolinium-based contrast agents (GCAs), which are extracellular contrast agents capable of T1 shortening, further refine the diagnostic capability by measuring the postcontrast T1 to calculate the extracellular volume.8
See Article by Haberkorn et al
CMR late gadolinium enhancement (LGE) is the current gold standard for noninvasive quantification of the myocardial infarct size and fibrosis.9 However, LGE requires an intravenous application of GCAs. Besides the contraindication in the setting of severe renal dysfunction, there is an ongoing U.S. Food and Drug Administration …