Table 4 Assumptions of gadolinium-contrast MRI

Gadolinium decreases T1 relaxation time which appears as increased intensity on T1-weighted images. The concentration of gadolinium in a tissue is proportional to the T1 signal intensity. By scanning before and after gadolinium infusion, the amount of gadolinium which was extravasated can be qualitatively estimated by increased T1 intensity, i.e. enhancement.

DCE-MRI provides a quantitative measurement of BBB leakage. In DCE-MRI, an image is acquired pre-contrast infusion and then multiple images are acquired during contrast infusion. The multiple T1 values are used to calculate the rate at which T1 signal intensity increases during infusion. This provides a quantitative measure of how quickly gadolinium extravasates, i.e. the permeability, named the volume transfer constant (K_trans).