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

@entity5 @entity1 @entity11 @entity734
BACKGROUND: To investigate the evolution of T1 in @entity5 and the necessity of baseline T1 (T1 (0)) mapping for the accurate estimation of kinetic parameters during standard therapy using dynamic contrast enhanced (DCE) MRI in @entity1 with high-grade @entity11 (HGG). METHODS: Longitudinal DCE-MRI was performed in 23 @entity1 (196 scans) with confirmed HGG. Kinetic parameters were derived from the extended Tofts model and analyzed both using fixed and pixel-wise T1 (0) values estimated from a Look-Locker sequence. Median @entity5 T1 value from all scans was used for fixed T1 (0) analysis. @entity734 of accurate T1 (0) mapping for the estimation of the kinetic parameters was further investigated through computer simulations and histogram analysis. RESULTS: T1 in @entity5 increased significantly during and after treatment (P < 0.001). There was a linear correlation between the error in 1/T1 (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 T1 (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 T1 (0) value. No effect of T1 (0) histogram distribution on K(trans) was observed (P = 0.52). CONCLUSION: Temporal changes in the median kinetic parameters in @entity5 were equally well described using pixel-wise and fixed T1 (0) despite an increase in T1 (0) over time, suggesting that T1 mapping is not generally required in DCE-MRI based monitoring of @entity11 @entity1 . J. Magn. Reson. Imaging 2015;42:97-104.    2014 Wiley Periodicals, Inc.
