Association between pharmacokinetic parameters from DCE-MRI and metabolic parameters from dynamic 18F-fluoromethylcholine PET in human brain glioma

Dynamic contrast-enhanced (DCE) MRI allows tissue perfusion quantication with the acquisition of T1-weighted images before, during and after injection of a gadolinium-based contrast reagent (CR). Data is frequently modelled by the Tofts model (TM), which embeds the implicit assumption that equilibrium transcytolemmal water exchange is innitely fast . The eect of water exchange on the MRI signal amplitude is incorporated by the shutter speed model (SSM), which introduces a further pharmacokinetic parameter τ , the mean intracellular water lifetime . The Tofts pharmacokinetic assumes a linear dependence of R on [CR]. However, tissue parenchyma cannot be considered as a single homogeneous solution. A voxel in MR will contain dierent tissue compartments which may aect the signal and are considered in the modication for the SSM . We assess the robustness of the two methods by studying them in tumour lesions and contra-lateral white matter (CWM).