Quantitative Assessment of Tumor Cell Proliferation in Brain Gliomas with Dynamic Contrast-Enhanced MRI

Rationale and Objectives: This study aimed to investigate whether volume transfer constant (K-trans) and volume of extravascular extracellular space per unit volume of tissue (V-e) derived from dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) could quantitatively assess the tumor proliferation index (KI-67) of gliomas non invasively. Materials and Methods: The preoperative DCE MRI data of 69 patients with pathologically confirmed glioma (28, 8, and 33 cases in grades II, III, and IV) were retrospectively reviewed. The maximal K (trans) and V-e were measured in the tumor body. The immunohistochemistry was used to detect the expression of Ki-67 proteins in glioma specimens. The Mann-Whitney U test was applied to analyze the differences in K-trans, V-e, and Ki-67 index across histologically defined glioma grades. Spearman correlation was performed between K-trans, V-e, and Ki-67 index. The receiver operating characteristic curve analysis was used to determine the cutoff values of K-trans and V-e in distinguishing different Ki-67 index expression levels. Results: K-trans, V-e, and Ki-67 index of grade II (0.027 min(-1), 0.065, 4.04%) were significantly lower than those of grade III (0.093 min(-1), 0.297, 25.13%) and IV (0.100 min(-1), 0.299, 25.37%). Both K-trans and V-e significantly correlated with the Ki-67 index in all tumors and high-grade gliomas (HGGs, grade III and IV). The receiver operating characteristic curve analysis revealed that the cutoff values for K-trans (0.079 min(-1)) and V-e (0.249) provided the best combination of sensitivity and specificity to distinguish the gliomas with high Ki-67 index from those with low Ki-67 index. Conclusion: The DCE MRI-derived parameters were valuable in assessing the tumor cell proliferation in HGG noninvasively.