Coomparative study of methods for determining vascular permeability and blood volume in human gliomas

Purpose: To characterize human gliomas using T-1-weighted dynamic contrast-enhanced MRI (DCE-MRI), and directly compare three pharmacokinetic analysis techniques: a conventional established technique and two novel techniques that aim to reduce erroneous overestimation of the volume transfer constant between plasma and the extravascular extracellular space (EES) (K-trans) in areas of high blood volume. Materials and Methods: Eighteen patients with high-grade gliomas underwent DCE-MRI. Three kinetic models were applied to estimate K-trans and fractional blood plasma volume (v(p)). We applied the Tofts and Kermode (TK) model without arterial input function (AIF) estimation, the TK model modified to include v(p) and AIF estimation (mTK), and a "first pass" variant of the TK model (FP). Results: K-TK values were considerably higher than K-mTK and K-FP values (P < 0.001). K-mTK and K-FP were more comparable and closely correlated (p = 0.744), with K-mTK generally higher than K-FP (P < 0.001). Estimates of v(p(mTK)) and v(p(FP)) also showed a significant difference (P < 0.001); however, these values were very closely correlated (p = 0.901). K-TK parameter maps showed "pseudopermeability" effects displaying numerous vessels. These were not visualized on K-mTK and K-FP maps but appeared on the corresponding vp maps, indicating a failure of the TK model in commonly occurring vascular regions. Conclusion: Both of the methods that incorporate a measured AIF and an estimate of v(p) provide similar pathophysiological information and avoid erroneous overestimation of K-trans in areas of significant vessel density, and thus allow a more accurate estimation of endothelial permeability. (C) 2004 Wiley-Liss, Inc.