%0 Journal Article
%A Völzke, Yannik
%A Akbey, Suzan
%A Löwen, Daniel
%A Pracht, Eberhard Daniel
%A Stirnberg, Rüdiger
%A Gras, Vincent
%A Boulant, Nicolas
%A Zaiss, Moritz
%A Stöcker, Tony
%T Calibration-free whole-brain CEST imaging at 7T with parallel transmit pulse design for saturation homogeneity utilizing universal pulses (PUSHUP).
%J Magnetic resonance in medicine
%V 93
%N 2
%@ 1522-2594
%C New York, NY [u.a.]
%I Wiley-Liss
%M DZNE-2024-01380
%P 630 - 642
%D 2025
%X 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 
%X <br clear="all" /><table border="0" width="100%"><tr><td>
%X <table align="center" cellspacing="0"  cellpadding="2"><tr><td nowrap="nowrap" align="center">
%X  B<sub>1</sub><sup>rms</sup> </td></tr></table>
%X </td></tr></table>
%X 
%X  . PUSHUP homogenizes the saturation B 1 rms 
%X <br clear="all" /><table border="0" width="100%"><tr><td>
%X <table align="center" cellspacing="0"  cellpadding="2"><tr><td nowrap="nowrap" align="center">
%X  B<sub>1</sub><sup>rms</sup> </td></tr></table>
%X </td></tr></table>
%X 
%X  by using multiple saturation pulses with alternating B 1 
%X <br clear="all" /><table border="0" width="100%"><tr><td>
%X <table align="center" cellspacing="0"  cellpadding="2"><tr><td nowrap="nowrap" align="center">
%X  B<sub>1</sub> </td></tr></table>
%X </td></tr></table>
%X 
%X  -shims. Using a database of B 1 
%X <br clear="all" /><table border="0" width="100%"><tr><td>
%X <table align="center" cellspacing="0"  cellpadding="2"><tr><td nowrap="nowrap" align="center">
%X  B<sub>1</sub> </td></tr></table>
%X </td></tr></table>
%X 
%X  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 
%X <br clear="all" /><table border="0" width="100%"><tr><td>
%X <table align="center" cellspacing="0"  cellpadding="2"><tr><td nowrap="nowrap" align="center">
%X  B<sub>1</sub> </td></tr></table>
%X </td></tr></table>
%X 
%X  -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 
%X <br clear="all" /><table border="0" width="100%"><tr><td>
%X <table align="center" cellspacing="0"  cellpadding="2"><tr><td nowrap="nowrap" align="center">
%X  B<sub>1</sub> </td></tr></table>
%X </td></tr></table>
%X 
%X  -correction, PUSHUP CEST maps were artifact-free throughout the whole brain. A 1-point retrospective B 1 
%X <br clear="all" /><table border="0" width="100%"><tr><td>
%X <table align="center" cellspacing="0"  cellpadding="2"><tr><td nowrap="nowrap" align="center">
%X  B<sub>1</sub> </td></tr></table>
%X </td></tr></table>
%X 
%X  -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 
%X <br clear="all" /><table border="0" width="100%"><tr><td>
%X <table align="center" cellspacing="0"  cellpadding="2"><tr><td nowrap="nowrap" align="center">
%X  B<sub>1</sub> </td></tr></table>
%X </td></tr></table>
%X 
%X  -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.
%K Humans
%K Brain: diagnostic imaging
%K Magnetic Resonance Imaging: methods
%K Algorithms
%K Image Processing, Computer-Assisted: methods
%K Phantoms, Imaging
%K Calibration
%K Adult
%K Male
%K Female
%K CEST (Other)
%K magnetization transfer (Other)
%K parallel transmit (Other)
%K ultra‐high field (Other)
%K universal pulses (Other)
%F PUB:(DE-HGF)16
%9 Journal Article
%2 pmc:PMC11604840
%$ pmid:39301770
%R 10.1002/mrm.30305
%U https://pub.dzne.de/record/273901