Simultaneous acquisition of perfusion and permeability from corrected relaxation rates with dynamic susceptibility contrast dual gradient echo

This study compared two methods, corrected (separation of T₁ and T₂ effects) and uncorrected, in order to determine the suitability of the perfusion and permeability measures through ΔR ₂ and ΔR₁ analyses. A dynamic susceptibility contrast dual gradient echo (DSC-DGE) was used to image the fixed phantoms and flow phantoms (Sephadex perfusion phantoms and dialyzer phantom for the permeability measurements). The results confirmed that the corrected relaxation rate was linearly proportional to gadolinium-diethyltriamine pentaacetic acid (Gd-DTPA) concentration, whereas the uncorrected relaxation rate did not in the fixed phantom and simulation experiments. For the perfusion measurements, it was found that the correction process was necessary not only for the ΔR₁ time curve but also for the ΔR₂ time curve analyses. Perfusion could not be measured without correcting the ΔR₂ time curve. The water volume, which was expressed as the perfusion amount, was found to be closer to the theoretical value when using the corrected ΔR₁ curve in the calculations. However, this may occur in the low concentration of Gd-DTPA in tissue used in this study. For the permeability measurements based on the two-compartment model, the permeability factor (k_ev; e = extravascular, v = vascular) from the outside to the inside of the hollow fibers was greater in the corrected ΔR ₁ method than in the uncorrected ΔR₁ method. The differences between the corrected and the uncorrected ΔR₁ values were confirmed by the simulation experiments. In conclusion, this study proposes that the correction for the relaxation rates, ΔR₂ and ΔR₁, is indispensable in making accurate perfusion and permeability measurements, and that DSC-DGE is a useful method for obtaining information on perfusion and permeability, simultaneously.