Whole‐brain quantitative CEST MRI at 7T using parallel transmission methods and correction
Open Access
- 26 February 2021
- journal article
- research article
- Published by Wiley in Magnetic Resonance in Medicine
- Vol. 86 (1), 346-362
- https://doi.org/10.1002/mrm.28745
Abstract
Purpose To enable whole‐brain quantitative CEST MRI at ultra‐high magnetic field strengths (B0 ≥ 7T) within short acquisition times. Methods Multiple interleaved mode saturation (MIMOSA) was combined with fast online‐customized (FOCUS) parallel transmission (pTx) excitation pulses and correction to achieve homogenous whole‐brain coverage. Examinations of 13 volunteers were performed on a 7T MRI system with 3 different types of pulse sequences: (1) saturation in circular polarized (CP) mode and CP mode readout, (2) MIMOSA and CP readout, and (3) MIMOSA and FOCUS readout. For comparison, the inverse magnetic transfer ratio metric for relayed nuclear Overhauser effect and amide proton transfer were calculated. To investigate the number of required acquisitions for a good correction, 4 volunteers were measured with 6 different B1 amplitudes. Finally, time point repeatability was investigated for 6 volunteers. Results MIMOSA FOCUS sequence using correction, with both single and multiple points, reduced inhomogeneity of the CEST contrasts around the occipital lobe and cerebellum. Results indicate that the most stable inter‐subject coefficient of variation was achieved using the MIMOSA FOCUS sequence. Time point repeatability of MIMOSA FOCUS with single‐point correction showed a maximum coefficient of variation below 8% for 3 measurements in a single volunteer. Conclusion A combination of MIMOSA FOCUS with a single‐point correction can be used to achieve quantitative CEST measurements at ultra‐high magnetic field strengths. Compared to previous correction methods, acquisition time can be reduced as additional scans required for correction can be omitted.Funding Information
- H2020 European Research Council (667510)
- Friedrich-Alexander-Universität Erlangen-Nürnberg (EFI MIRACLE project)
This publication has 44 references indexed in Scilit:
- Prospective motion correction in brain imaging: A reviewMagnetic Resonance in Medicine, 2012
- In vivo three‐dimensional whole‐brain pulsed steady‐state chemical exchange saturation transfer at 7 TMagnetic Resonance in Medicine, 2011
- Quantitative separation of CEST effect from magnetization transfer and spillover effects by Lorentzian-line-fit analysis of z-spectraJournal of Magnetic Resonance, 2011
- Optimizing pulsed‐chemical exchange saturation transfer imaging sequencesMagnetic Resonance in Medicine, 2011
- Optimization of pulse train presaturation for CEST imaging in clinical scannersMagnetic Resonance in Medicine, 2011
- Fast 3D chemical exchange saturation transfer (CEST) imaging of the human brainMagnetic Resonance in Medicine, 2010
- Quantifying exchange rates in chemical exchange saturation transfer agents using the saturation time and saturation power dependencies of the magnetization transfer effect on the magnetic resonance imaging signal (QUEST and QUESP): Ph calibration for poly‐L‐lysine and a starburst dendrimerMagnetic Resonance in Medicine, 2006
- Unified segmentationNeuroImage, 2005
- Quantitative description of proton exchange processes between water and endogenous and exogenous agents for WEX, CEST, and APT experimentsMagnetic Resonance in Medicine, 2004
- Image Quality Assessment: From Error Visibility to Structural SimilarityIEEE Transactions on Image Processing, 2004