| dc.description.abstract | Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a method that can be used to quantitatively and qualitatively assess physiological characteristics of tissue. Quantitative DCE-MRI requires an estimate of the time rate of change of the concentration of the contrast agent in the blood plasma; the so-called vascular input function, or VIF. Measuring the VIF is notoriously difficult as it requires high temporal resolution images limiting the achievable number of slices, field-of-view, spatial resolution, and signal-to-noise. Alternatively, a population-averaged VIF could be used to mitigate the acquisition demands in studies aimed to investigate, for example, tumor vascular characteristics. Eight rats inoculated with C6 glioma cells underwent DCE-MRI at 9.4T. A set of dynamic spoiled gradient-echo images was acquired before, during, and after a bolus injection of Gd-DTPA (Magnevist, Wayne, NJ). Pharmacokinetic parameters (Ktrans, ve, and vp) were extracted from signal-time curves of tumor tissue using both individual and population-averaged VIFs. Standard model voxel values of Ktrans and ve estimated using a population-averaged VIF have a high correlation (concordance correlation coefficient > 0.7852) and a strong linear relationship (Pearson correlation coefficient > 0.9802) with Ktrans and ve values estimated using an individual VIF. Additionally, the extended model voxel values of Ktrans, ve, and vp also showed a high correlation (concordance correlation coefficient > 0.6931) and a strong linear relationship (Pearson correlation coefficient > 0.9159) supporting the use of a population based VIF in DCE-MRI. | |
