Validation of Dynamic Contrast-Enhanced Magnetic Resonance Imaging-Derived Vascular Permeability Measurements Using Quantitative Autoradiography in the RG2 Rat Brain Tumor Model

摘要

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is widely used to evaluate tumor permeability, yet measurements have not been directly validated in brain tumors. Our purpose was to compare estimates of forward leakage K^trans derived from DCE-MRI to the estimates K obtained using [¹⁴C]aminoisobutyric acid quantitative autoradiography ([¹⁴C]AIB QAR), an established method of evaluating blood-tumor barrier permeability. Both DCE-MRI and [¹⁴C]AIB QAR were performed in five rats 9 to 11 days following tumor implantation. K^trans in the tumor was estimated from DCE-MRI using the threeparameter general kinetic model and a measured vascular input function. Ki was estimated from QAR data using regions of interest (ROI) closely corresponding to those used to estimate K^trans. K^trans and Ki correlated with each other for two independent sets of central tumor ROI (R = 0.905, P = .035; R = 0.933, P = .021). In an additional six rats, K^trans was estimated on two occasions to show reproducibility (intraclass coefficient = 0.9993; coefficient of variance = 6.07%). In vivo blood-tumor permeability parameters derived from DCE-MRI are reproducible and correlate with the gold standard for quantifying blood tumor barrier permeability, [¹⁴C]AIB QAR.