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The impact of reliable pre-bolus T1 measurements or a fixed T1 value in the assessment of glioma patients with Dynamic Contrast Enhancing MRI

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Purpose: Accurate quantification of hemodynamic parameters using Dynamic Contrast Enhanced MRI (DCE) requires a measurement of tissue T1 prior to contrast injection (T1). We evaluate (i) T1 estimation using the variable flip angle (VFA) and the saturation recovery (SR) techniques and (ii) investigate if accurate estimation of DCE parameters outperform a time-saving approach with a pre-defined T1 value when differentiating high- from low-grade gliomas. Methods: (i) The accuracy and precision of T1 measurements, acquired by VFA and SR was investigated by computer simulations and in glioma patients using an equivalence test (p > 0.05 showing significant difference). (ii) Ktrans, CBF, and Vp were calculated in 42 glioma patients using fixed T1 of 1500ms or an individual T1 measured using SR. The areas under the receiver operating characteristic curves (AUC) were used as measure for accuracy to differentiate tumor grade. Results: The T1 values obtained by VFA showed larger variation compared to those obtained using SR both in the digital phantom and the human data (p > 0.05). Although a fixed T1 introduced a bias into the DCE calculation, this had only minor impact on the accuracy differentiating high-grade from low-grade gliomas, assessed by ROC curves (AUCfix=0.906 and AUCind=0.884 for Ktrans; AUCfix=0.863 and AUCind=0.856 for Vp; p for AUC comparison > 0.05). Conclusion: T1 measurements by VFA were less precise, and the SR method is preferable, when accurate parameter estimation is required. Semi-quantitative DCE values, based on pre-defined T1 values, were sufficient to perform tumor grading in our study.
Original languageEnglish
Pages (from-to)561-72
Publication statusPublished - 2015

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