The impact of reliable prebolus T 1 measurements or a fixed T 1 value in the assessment of glioma patients with dynamic contrast enhancing MRI.
BACKGROUND
Accurate quantification of hemodynamic parameters using dynamic contrast enhanced (DCE) MRI requires a measurement of tissue T 1 prior to contrast injection (T 1). We evaluate (i) T 1 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 predefined T 1 value when differentiating high- from low-grade gliomas.


METHODS
The accuracy and precision of T 1 measurements, acquired by VFA and SR, were investigated by computer simulations and in glioma patients using an equivalence test (p > 0.05 showing significant difference). The permeability measure, K trans, cerebral blood flow (CBF), and - volume, V p, were calculated in 42 glioma patients, using fixed T 1 of 1500 ms or an individual T 1 measurement, using SR. The areas under the receiver operating characteristic curves (AUCs) were used as measures for accuracy to differentiate tumor grade.


RESULTS
The T 1 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 T 1 introduced a bias into the DCE calculation, this had only minor impact on the accuracy differentiating high-grade from low-grade gliomas, (AUCfix = 0.906 and AUCind = 0.884 for K trans; AUCfix = 0.863 and AUCind = 0.856 for V p; p for AUC comparison > 0.05).


CONCLUSIONS
T 1 measurements by VFA were less precise, and the SR method is preferable, when accurate parameter estimation is required. Semiquantitative DCE values, based on predefined T 1 values, were sufficient to perform tumor grading in our study.
Dept. of Neuroradiology, Aarhus University Hospital, Nørrebrogade 44, DK-8000, Aarhus, Denmark, anntie@rm.dk.
Anna
A
Tietze
Kim
K
Mouridsen
Irene Klærke
IK
Mikkelsen
D001932:Brain Neoplasms / Q000473:pathology*; D002560:Cerebrovascular Circulation; D003198:Computer Simulation; D003287:Contrast Media; D005910:Glioma / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D060787:Neoplasm Grading; D011237:Predictive Value of Tests; D012372:ROC Curve
D003287:Contrast Media