Journal Article

DZNE-2024-01380

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Calibration-free whole-brain CEST imaging at 7T with parallel transmit pulse design for saturation homogeneity utilizing universal pulses (PUSHUP).

Völzke, Y. (First author)DZNE* ; Akbey, S.DZNE* ; Löwen, D.DZNE* ; Pracht, E. D.DZNE* ; Stirnberg, R.DZNE* ; Gras, V. ; Boulant, N. ; Zaiss, M. ; Stöcker, T. (Last author)DZNE*

2025
Wiley-Liss New York, NY [u.a.]

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Please use a persistent id in citations: doi:10.1002/mrm.30305

Abstract: Chemical exchange saturation transfer (CEST) measurements at ultra-high field (UHF) suffer from strong saturation inhomogeneity. Retrospective correction of this inhomogeneity is possible to some extent, but requires a time-consuming repetition of the measurement. Here, we propose a calibration-free parallel transmit (pTx)-based saturation scheme that homogenizes the saturation over the imaging volume, which we call PUlse design for Saturation Homogeneity utilizing Universal Pulses (PUSHUP).Magnetization transfer effects depend on the saturation B 1 rms $$ {\mathrm{B}}_1^{\mathrm{rms}} $$ . PUSHUP homogenizes the saturation B 1 rms $$ {\mathrm{B}}_1^{\mathrm{rms}} $$ by using multiple saturation pulses with alternating B 1 $$ {\mathrm{B}}_1 $$ -shims. Using a database of B 1 $$ {\mathrm{B}}_1 $$ maps, universal pulses are calculated that remove the necessity of time-consuming, subject-based pulse calculation during the measurement.PUSHUP was combined with a whole-brain three-dimensional-echo planar imaging (3D-EPI) readout. Two PUSHUP saturation modules were calculated by either applying whole-brain or cerebellum masks to the database maps. The saturation homogeneity and the group mean CEST amplitudes were calculated for different B 1 $$ {\mathrm{B}}_1 $$ -correction methods and were compared to circular polarized (CP) saturation in five healthy volunteers using an eight-channel transmit coil at 7 Tesla.In contrast to CP saturation, where accurate CEST maps were impossible to obtain in the cerebellum, even with extensive B 1 $$ {\mathrm{B}}_1 $$ -correction, PUSHUP CEST maps were artifact-free throughout the whole brain. A 1-point retrospective B 1 $$ {\mathrm{B}}_1 $$ -correction, that does not need repeated measurements, sufficiently removed the effect of residual saturation inhomogeneity.The presented method allows for homogeneous whole-brain CEST imaging at 7 Tesla without the need of a repetition-based B 1 $$ {\mathrm{B}}_1 $$ -correction or online pulse calculation. With the fast 3D-EPI readout, whole-brain CEST imaging with 45 saturation offsets is possible at 1.6 mm resolution in under 4 min.

Keyword(s): Humans (MeSH) ; Brain: diagnostic imaging (MeSH) ; Magnetic Resonance Imaging: methods (MeSH) ; Algorithms (MeSH) ; Image Processing, Computer-Assisted: methods (MeSH) ; Phantoms, Imaging (MeSH) ; Calibration (MeSH) ; Adult (MeSH) ; Male (MeSH) ; Female (MeSH) ; CEST ; magnetization transfer ; parallel transmit ; ultra‐high field ; universal pulses

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Contributing Institute(s):

1. MR Physics (AG Stöcker)

Research Program(s):

1. 354 - Disease Prevention and Healthy Aging (POF4-354) (POF4-354)

Appears in the scientific report 2024

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Database coverage:
; ; ; BIOSIS Previews ; Biological Abstracts ; Clarivate Analytics Master Journal List ; Current Contents - Clinical Medicine ; Current Contents - Life Sciences ; DEAL Wiley ; Essential Science Indicators ; IF < 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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