Development of an echo‐shifted, multi‐echo, gradient‐echo sequence for T2 * quantification of slow‐relaxing water pools

Magnetic Resonance in Medicine, vol. 94, pp. 2057–2070

Abstract

Abstract Purpose Although conventional multi‐echo gradient‐echo (GRE) sequences effectively quantify short and intermediate T2* in brain tissue, and general interest in cerebrospinal fluid (CSF) is growing due to its association with the glymphatic system, quantifying T2* in CSF remains underexplored. Accurate quantification of the slow‐relaxing water pools requires imaging at long echo times, significantly increasing acquisition time. This study proposes a novel sequence capable of quantifying the entire range of T2* without prolonged acquisition time, mapping T2* in both CSF and brain tissue. Methods The proposed echo‐shifted, multi‐echo GRE (ES‐mGRE) combines the conventional multi‐echo GRE sequence with an echo‐shifting technique. Additional gradients are introduced, producing echoes in the next sub–repetition time interval. Results ES‐mGRE generates artifact‐free images at both short and long echo times without extending acquisition time. Increasing the area of the additional gradients enhances diffusion sensitivity, allowing simultaneous quantification of T2* and D in CSF. The mean T2* of white matter and gray matter is 55.9 ms and 51.5 ms at 3 T, respectively. The mean T2* in the ventricles is 234.5 ms. The simultaneously quantified mean D value of 3.07 μm2/ms is closely aligned with the reference diffusivity. Conclusion We demonstrate that the proposed ES‐mGRE sequence can effectively quantify the T2* of both CSF and brain tissue while also providing simultaneous diffusion information.

Authors 5

1. Seonyeong Shin Aachen

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Institute of Neuroscience and Medicine 4, INM‐4, Forschungszentrum Jülich Jülich Germany

   RWTH Aachen University Aachen Germany

2. Ana‐Maria Oros‐Peusquens

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Neuroscience and Medicine 4, INM‐4, Forschungszentrum Jülich Jülich Germany

3. Seong Dae Yun

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Neuroscience and Medicine 4, INM‐4, Forschungszentrum Jülich Jülich Germany

4. Ezequiel Farrher

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Neuroscience and Medicine 4, INM‐4, Forschungszentrum Jülich Jülich Germany

5. Nadim Jon Shah corresponding Aachen Department of Neurology

   Forschungszentrum Jülich · Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Department of Neurology RWTH Aachen University Aachen Germany

   Institute of Neuroscience and Medicine 11, INM‐11, JARA, Forschungszentrum Jülich Jülich Germany

   Institute of Neuroscience and Medicine 4, INM‐4, Forschungszentrum Jülich Jülich Germany

   JARA ‐ BRAIN ‐ Translational Medicine Aachen Germany