Effect of a gadodiamide contrast agent on the reliability of brain tissue T-1 measurements

To determine whether brain spin-lattice relaxation time (T-1) can routinely be measured after contrast-agent injection, we measured T-1 by a precise a nd accurate inversion-recovery (PAIR) method in five brain tumor patients, before and again after contrast-agent injection. The T-1 in at least 20 reg ions of interest (ROIs) was measured in each patient, avoiding areas of con trast enhancement visible by conventional MR imaging. Contrast-agent inject ion reduced T-1 in 51 regions of interest in white matter by less than 1% ( not significant), and in 50 regions of interest in gray matter by less than 2% (p = 0.001), Pixel-by-pixel plots demonstrate that T-1 is reduced subst antially in extra-parenchymal tissues, but not in brain tissues. Therefore, T-1 mapping with the precise and accurate inversion-recovery method can ro utinely be done after contrast injection. Our results suggest that the prec ise and accurate inversion-recovery method is not sensitive to the T-1 of b lood in the presence of an intact blood-brain barrier, although a substanti al T-1 reduction does occur in the absence of a blood-brain barrier. (C) 19 99 Elsevier Science Inc.