Analysis of the Spin and Gradient Echo (SAGE) Sequence for DSC-MRI in Rat Brain Tumors

Ashley M. Stokes¹, ², Christopher C. Quarles¹, ²

A combined spin- and gradient-echo (SAGE) EPI method was applied in a rat glioma model to obtain absolute ΔR₂, ΔR₂* and ΔR₁ curves, thereby permitting derivation of dynamic susceptibility contrast (DSC) parameters. T₁-insensitive estimates of R₂ and R₂^* were acquired with SAGE and compared to conventional GE and SE DSC parameters, as well as independently measured R₂ and R₂^*. The normal brain GE and SAGE ΔR₂^* curves produced similar relative cerebral blood volume (rCBV) values, while tumor leakage effects led to substantially underestimated rCBV values from the GE ΔR₂^* curve. Dynamic SAGE acquisition can provide improved perfusion and permeability information.