Diffusion-Weighted, Readout-Segmented EPI with Synthesized T2- and T2*-Weighted Images

Purpose: Diffusion-weighted Imaging (DWI) using readout-segmented EPI (rs-EPI) with 2D navigator correction [1] is an alternative to standard single-shot EPI (ss-EPI) that improves image quality by reducing susceptibility artifacts and allowing a higher spatial resolution. This improved image quality raises the possibility that the low b-value image could be used to replace a separate T2-weighted acquisition and reduce the overall examination time. The EPI readout used by the rs-EPI sequence is much shorter than that of ss-EPI, resulting in a significant reduction in echo time. Whilst this is beneficial for DWI because of the improved SNR, it can be a disadvantage for providing T2-weighted images because the TE is short compared to the value used in standard clinical, T2-weighted protocols. The purpose of this study was to implement a prototype of a modified navigator-corrected rs-EPI sequence that provides an additional T2-weighted image with a flexible, user-defined echo time. The proposed modification achieves this with minimal increase in the overall scan time and without sacrificing the data at short echo time provided by the original sequence. In addition, the additional image can be generated with T2 -weighting, making it potentially useful for identifying hemorrhage.