Dynamic contrast-enhanced MRI using Gd-DTPA: Interindividual variability of the arterial input function and consequences for the assessment of kinetics in tumors

Gd-DTPA kinetics in arterial brood was investigated by dynamic MRI in 47 pa tients with malignant and benign mammary tumors. Signal enhancement was mon itored for 10 min after the beginning of a 1-min infusion of 0.1 mmol/kg Gd -DTPA. Kinetics in blood was biexponential with median half-lives of 21 sec and 11.1 min, respectively. Peak signal enhancement and the area under the signal enhancement-time curve varied 2,5- and 3.7-fold between patients. T he shortest mean residence time in one of up to three tumor compartments, M RT*, was estimated using either the individual (reference) or a mean popula tion (surrogate) arterial input function (AIF). MRT* (reference estimate) w as 1.0 (0-1.5), 1.9 (1.5-2.3), and 2.5 (2.3-2.8) min in carcinomas, fibroad enomas, and mastopathies, respectively (median and interquartile distance). Surrogate estimates were unbiased but differed from the reference estimate s 1.5-fold or more in 23% of cases. AIFs should be monitored individually i f accurate estimates of individual MRT* are desired. (C) 2001 Wiley-Liss, I nc.