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

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 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 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.

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.

The DCE MRI-derived parameters were valuable in assessing the tumor cell proliferation in HGG noninvasively.