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Zusammenfassung:
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 urn:x-wiley:07403194:media:mrm27866:mrm27866-math-0002 distribution in order to optimize urn:x-wiley:07403194:media:mrm27866:mrm27866-math-0003 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 urn:x-wiley:07403194:media:mrm27866:mrm27866-math-0004 distribution analysis, we conclude that 3 urn:x-wiley:07403194:media:mrm27866:mrm27866-math-0005 sampling points allow for sufficient compensation of urn:x-wiley:07403194:media:mrm27866:mrm27866-math-0006 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 urn:x-wiley:07403194:media:mrm27866:mrm27866-math-0007 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.