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

Abstract

This study aimed to investigate whether volume transfer constant (Ktrans) and volume of extravascular extracellular space per unit volume of tissue (Ve) derived from dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) could quantitatively assess the tumor proliferation index (Ki-67) of gliomas noninvasively. 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 Ktrans and Ve 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 Ktrans, Ve, and Ki-67 index across histologically defined glioma grades. Spearman correlation was performed between Ktrans, Ve, and Ki-67 index. The receiver operating characteristic curve analysis was used to determine the cutoff values of Ktrans and Ve in distinguishing different Ki-67 index expression levels. Ktrans, Ve, 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 Ktrans and Ve 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 Ktrans (0.079 min-1) and Ve (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. The DCE MRI-derived parameters were valuable in assessing the tumor cell proliferation in HGG noninvasively.