R2/R2* Estimation Errors in Combined Gradient- And Spin-Echo EPI Sequences Due to Slice-Profile Differences Between RF Pulses

Heiko Schmiedeskamp¹, Matus Straka¹, Roland Bammer¹

There is an increased interest in combined gradient-echo and spin-echo pulse sequences for applications in PWI and fMRI, facilitated by the differences in signal decay of gradient echoes and spin echoes depending on the mean vessel size within a voxel. This abstract deals with issues of mismatched slice profiles in such pulse sequences between the 90 excitation pulse and the 180 refocusing pulse, and it introduces a scaling factor for improved T1-independent R2 and R2* quantification.