Glioblastoma Treated with Concurrent Radiation Therapy and Temozolomide Chemotherapy: Differentiation of True Progression from Pseudoprogression with Quantitative Dynamic Contrast-enhanced MR Imaging

To explore the role of dynamic contrast material-enhanced magnetic resonance (MR) imaging in the differentiation of true progression from pseudoprogression in patients with glioblastoma on the basis of findings in entirely newly developed or enlarged enhancing lesions after concurrent radiation therapy and chemotherapy with temozolomide and to evaluate the diagnostic performance of the quantitative pharmacokinetic parameters obtained at dynamic contrast-enhanced MR imaging, such as the volume transfer constant (K(trans)), the extravascular extracellular space per unit volume of tissue(ve), and the blood plasma volume per unit volume of tissue(vp).This prospective study had institutional review board approval; written informed consent was obtained from all patients. Thirty-three patients with histopathologically proven glioblastoma who had undergone concurrent radiation therapy and chemotherapy with temozolomide were included. Dynamic contrast-enhanced MR imaging-derived pharmacokinetic parameters, including K(trans), ve, and vp, were calculated for newly developed or enlarged enhancing lesions. Pharmacokinetic parameters were compared between the true progression (n = 17) and pseudoprogression (n = 16) groups by using unpaired t tests and then multivariable analysis.The mean K(trans) and ve were higher in the true progression group than in the pseudoprogression group (mean K(trans), 0.44 min(-1) ± 0.25 [standard deviation] and 0.23 min(-1) ± 0.10 for true progression and pseudoprogression groups, respectively, P = .004; and mean ve, 1.26 ± 0.78 and 0.75 ± 0.49 for true progression and pseudoprogression groups, respectively, P = .034). Multivariable analysis showed that mean K(trans) was the only independently differentiating variable (P = .004).Dynamic contrast-enhanced MR imaging-derived pharmacokinetic parameters, including K(trans) and ve, in the entire newly developed or enlarged enhancing lesion may be useful objective diagnostic tools in the differentiation of true progression from pseudoprogression in patients with glioblastoma who have undergone concurrent radiation therapy and chemotherapy with temozolomide.