Three different cardiac magnetic resonance T1 maps are demonstrated. Native T1 and post-contrast T1 maps are generated by the signal intensity encoded within each voxel, depending on the T1 relaxation time; color coding according to T1 times is applied for visual reference. ECV% maps are generated using the formula ECV% = (Δ[1/T1myo]/Δ[1/T1blood]) × (1 − hematocrit), where Δ(1/T1) is the difference in myocardial or blood T1 pre-contrast and post-contrast. ECV% can be used to assess the proportion of the myocardium comprised by extracellular space. Note that there is significant overlap between health and disease with native and post-contrast T1, in contrast to ECV%. Graphs adapted from Chin et al. (59) by permission of Oxford University Press. ECV% = extracellular volume fraction; iECV = indexed extracellular volume.