Figure 1.

Top: Precontrast T₁ measurement of one subject using four separate IRss images at selected TIs. In vivo T₁ was estimated using ROIs and a least‐squares approximation to Eq. [3]. Bottom: T₁ calculation from a subject 15 minutes postinjection (0.2 mmol/kg) at 1.5T. The ratio method for calculating T₁ involves two IR images using two different TIs: TI_high = 650 msec and TI_low = 150 msec. The images were rescaled and then divided (TI_high/TI_low) to produce an intensity‐ratio map. A T₁ map was numerically calculated on a pixelwise basis using Eq. [4], assuming an appropriate T₁ value.