Table 2.

Semiquantitative metrics of DCE-MRI

Parameter	Definition	Unit
Peak enhancement (PE)	Peak relative signal enhancement (RSE), i.e., maximum signal difference (MSD) divided by signal baseline (SB), where MSD is the difference between the signal intensity at its maximum and SB
Time-to-peak (TTP)	Time at which PE occurs, minus bolus arrival time (BAT) in the feeding artery	min
Time-to-half-peak (TTHP)	Time at which half PE occurs before time at which PE occurs, mus BAT in the feeding artery	min
Wash-in-slope (WIS)	PE divided by TTP	min−1
Wash-out-slope (WOS)	Difference between PE and RSE at the last time point (Tend), which is divided by difference between Tend and time at which PE occurs, if the PE does not occur at Tend; Otherwise zero	min−1
Initial gradient (IG)	Gradient calculated by linear regression of all the RSEs between 10% PE and 70% PE	min−1
Washout gradient (WG)	Gradient calculated by linear regression of all the RSEs taken between 1 and 2 min elapsed from BAT in the feeding artery	min−1
Signal enhancement ratio (SER)	RSE at 0.5 min divided by RSE at 2.5 min, elapsed from BAT in the feeding artery
Initial area under the curve (IAUC)	Area under the RSE curve until a stipulated time point, elapsed from BAT in the feeding artery