Table 1 Definitions of technical terms in the field of parametric mapping of the heart
Term | Meaning |
|---|---|
T1 [ms] | Time constant representing the recovery of longitudinal magnetization (spin–lattice relaxation) |
Native T1 | T1 in the absence of an exogenous contrast agent |
T2 [ms] | Time constant representing the decay of transverse magnetization (spin-spin relaxation) |
T2* [ms] | Time constant representing the decay of transverse magnetization in the presence of local field inhomogeneities |
ECV [%] | Extracellular volume fraction, calculated by \( ECV=\frac{\left(\frac{1}{T1 my{o}_{postGd}}-\frac{1}{T1 my{o}_{native}}\right)}{\left(\frac{1}{T1 bloo{d}_{postGd}}-\frac{1}{T1 bloo{d}_{native}}\right)}\times \left(100- hematocrit\right) \) where myo = myocardium; blood = intracavitary blood pool; hematocrit = cellular volume fraction of blood [%] |
Synthetic ECV [%] | ECV where hematocrit is not measured by laboratory blood sampling but derived from blood T1 |
Parametric mapping | A process where a secondary image is generated in which each pixel represents a specific magnetic tissue property (T1, T2, or T2*) or a derivative such as ECV) derived from the spatially corresponding voxel of a set of co-registered magnetic resonance source images |