Gadolinium-DTPA as a contrast agent in MR imaging--theoretical projections and practical observations.

The theoretical basis for the use of paramagnetic agents to enhance proton relaxation is described. Factors of importance in the design of contrast agents are considered. Measurements of changes in T1 and T2 in vitro due to Gd3+-diethylenetriamine pentaacetic acid (DTPA) are used to predict changes in the intensity of transverse magnetisation seen with different sequences in magnetic resonance imaging. The use of Gd3+-DTPA in clinical cases is illustrated.