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Whole‐brain snapshot CEST imaging at 7 T using 3D‐EPI
Author(s) -
Akbey Suzan,
Ehses Philipp,
Stirnberg Rüdiger,
Zaiss Moritz,
Stöcker Tony
Publication year - 2019
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.27866
Subject(s) - snapshot (computer storage) , nuclear magnetic resonance , computer science , physics , operating system
Purpose The aim of this work is to develop a fast and robust CEST sequence in order to allow the acquisition of a whole‐brain imaging volume after a single preparation block (snapshot acquisition). Methods A 3D‐CEST sequence with an optimized 3D‐EPI readout module was developed, which acquires the complete k‐space data following a single CEST preparation for 1 saturation offset. Whole‐brain mapping of the Z‐spectrum with 2 mm isotropic resolution is achieved at 68 saturation frequencies in 5 minutes (4.33 s per offset). We analyzed the B 1 distribution in order to optimize B 1 correction and to provide accurate CEST quantification across the whole brain. Results We obtained maps for 3 different CEST contrasts from 4 healthy subjects. Based on our B 1 distribution analysis, we conclude that 3 B 1 sampling points allow for sufficient compensation of B 1 variations across most of the brain. Two brain regions, the cerebellum and the temporal lobes, are difficult to quantify at 7 T due to very low B 1 that was achieved in these regions. Conclusions The proposed sequence enables robust acquisition of 2 mm isotropic whole‐brain CEST maps at 7 Tesla within a total scan time of 16 minutes.