T1 in high-grade glioma and the influence of different measurement strategies on parameter estimations in DCE-MRI

BackgroundTo investigate the evolution of T-1 in tumor and the necessity of baseline T-1 (T-1(0)) mapping for the accurate estimation of kinetic parameters during standard therapy using dynamic contrast enhanced (DCE) MRI in patients with high-grade glioma (HGG). MethodsLongitudinal DCE-MRI was performed in 23 patients (196 scans) with confirmed HGG. Kinetic parameters were derived from the extended Tofts model and analyzed both using fixed and pixel-wise T-1(0) values estimated from a Look-Locker sequence. Median tumor T-1 value from all scans was used for fixed T-1(0) analysis. Dependence of accurate T-1(0) mapping for the estimation of the kinetic parameters was further investigated through computer simulations and histogram analysis. ResultsT(1) in tumor increased significantly during and after treatment (P < 0.001). There was a linear correlation between the error in 1/T-1(0) and the resulting error in estimated parameters in both simulations and clinical data (r(2) >0.98 for all parameters). A strong correlation between the estimated longitudinal change in all kinetic parameters obtained using pixel-wise and fixed T-1(0) was observed (r(2) > 0.84 for all parameters). Histogram analysis revealed a linear change (r(2) > 0.62) in K-trans normalized histogram peak height ratio as function of percentage deviation from the nominal T-1(0) value. No effect of T-1(0) histogram distribution on K-trans was observed (P = 0.52). ConclusionTemporal changes in the median kinetic parameters in tumor were equally well described using pixel-wise and fixed T-1(0) despite an increase in T-1(0) over time, suggesting that T-1 mapping is not generally required in DCE-MRI based monitoring of glioma patients. J. Magn. Reson. Imaging 2015;42:97-104. (c) 2014 Wiley Periodicals, Inc.