Commonly used model-free (semiquantitative) parameters for DCE-MRI analysis
| Parameter | Definition | Units |
|---|---|---|
| Area under curve | Area under the signal intensity or gadolinium dynamic curve | a.u.min or mmol.min/L |
| Relative signal intensity | St/S0 | NA |
| Initial slope or enhancement slope/rate | Maximum or average slope in the initial enhancement | a.u/min |
| Washout slope/rate | Maximum or average slope in the washout phase | a.u/min |
| Peak enhancement ratio or maximum signal enhancement ratio | (Smax − S0)/S0 | NA |
| Tmax or time to peak | Time from contrast arrival to peak | S |
| Maximum intensity–time ratio | PER/Tmax | S−1 |
Note:—St indicates MR signal intensity at time t; S0, precontrast signal intensity; Smax, maximum signal intensity; a.u, arbitrary unit; min, minute; PER, peak enhancement ratio; Tmax, time to maximum enhancement; NA, not applicable; S, seconds.