A comparison of K trans measurements obtained with conventional and first pass pharmacokinetic models in human gliomas

Purpose To compare in a group of patients with cerebral gliomas the estimates of K trans between a conventionally established pharmacokinetic model and a recently developed first pass method. Materials and Methods Glioma patients (23) were studied using T 1 ‐weighted dynamic contrast‐enhanced magnetic resonance imaging (MRI), and two alternative pharmacokinetic models were used for analysis to derive the volume transfer constant K trans . These were a modified version of the established model (yielding K TK ) and a recently published method based on first pass leakage profile (FP) of contrast bolus (yielding K fp ). Results We found a strong correlation between intra‐tumoral median K TK and K fp (rho = 0.650, P < 0.01), but the values from the conventional model were consistently and significantly higher (mean of inter‐tumoral K fp and K TK medians were 0.018 minute −1 and 0.284 minute −1 , respectively, P < 0.001). The spatial distribution of K TK and K fp showed poor correlation in the presence of large vascular structures and good correlation elsewhere. Conclusion K TK and K fp produce similar biologic information within voxels not dominated by vascular tissue. The FP method avoids erroneous overestimation of K trans in areas of significant intravascular contrast. Findings are in keeping with the predictions of previous mathematical simulations. J. Magn. Reson. Imaging 2004;19:527–536. © 2004 Wiley‐Liss, Inc.