Antiangiogenic Effect of Bevacizumab: Application of Arterial Spin-Labeling Perfusion MR Imaging in a Rat Glioblastoma Model

The usefulness of arterial spin-labeling for the evaluation of the effect of the antiangiogenic therapy has not been elucidated. Our aim was to evaluate the antiangiogenic effect of bevacizumab in a rat glioblastoma model based on arterial spin-labeling perfusion MR imaging. DSC and arterial spin-labeling perfusion MR imaging were performed by using a 9.4T MR imaging scanner in nude rats with glioblastoma. Rats were randomly assigned to the following 3 groups: control, 3-day treatment, and 10-day treatment after bevacizumab injection. One-way analysis of variance with a post hoc test was used to compare perfusion parameters (eg, normalized CBV and normalized CBF from DSC MR imaging and normalized CBF based on arterial spin-labeling) with microvessel area on histology. The Pearson correlations between perfusion parameters and microvessel area were also determined. All of the normalized CBV from DSC, normalized CBF from DSC, normalized CBF from arterial spin-labeling, and microvessel area values showed significant decrease after treatment (P < .001, P < .001, P = .005, and P < .001, respectively). In addition, normalized CBV and normalized CBF from DSC and normalized CBF from arterial spin-labeling strongly correlated with microvessel area (correlation coefficient, r = 0.911, 0.869, and 0.860, respectively; P < .001 for all). Normalized CBF based on arterial spin-labeling and normalized CBV and normalized CBF based on DSC have the potential for evaluating the effect of antiangiogenic therapy on glioblastomas treated with bevacizumab, with a strong correlation with microvessel area.