Electrophysiology Unit (EPU) 26.19 Practice Test

A key distinction of cardiac MRI is its ability to characterize heart tissue, not just image structure. In particular, MRI can detect fibrosis and myocardial remodeling. This is most clearly shown with late gadolinium enhancement: after gadolinium contrast is given, fibrotic or scarred tissue, which has an expanded extracellular space, takes up more contrast and remains bright on imaging, while normal myocardium clears it and appears darker. This pattern lets us identify prior infarcts, the extent and distribution of scar, and how the heart muscle has remodeled over time. MRI can also quantify tissue properties with T1/T2 mapping, giving detailed information about edema, fibrosis, and other tissue changes.

CT excels at detailed anatomy and coronary arteries, and can assess perfusion with contrast, but it does not routinely provide the same intrinsic tissue characterization as MRI. So, the unique feature of MRI relative to CT for the heart is its ability to reveal tissue fibrosis and remodeling, which is invaluable for diagnosing cardiomyopathies, viability assessment, and prognosis.