TY - JOUR
T1 - The use of variable delay multipulse chemical exchange saturation transfer for separately assessing different CEST pools in the human brain at 7T
AU - Schmitz-Abecassis, Bárbara
AU - Vinogradov, Elena
AU - Wijnen, Jannie P
AU - van Harten, Thijs
AU - Wiegers, Evita C
AU - Hoogduin, Hans
AU - van Osch, Matthias J P
AU - Ercan, Ece
N1 - Funding Information:
This study is part of the project “Non‐Invasive Characterization of Active Multiple Sclerosis Lesions Through Chemical Exchange Saturation Transfer (CEST) Imaging” (project no. 16862) financed by the Dutch Research Council (NWO) Talent Programme Veni. This work was also funded by the Medical Delta Cancer Diagnostics 3.0 program.
Publisher Copyright:
© 2021 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.
PY - 2022/2
Y1 - 2022/2
N2 - PURPOSE: Current challenges of in vivo CEST imaging include overlapping signals from different pools. The overlap arises from closely resonating pools and/or the broad magnetization transfer contrast (MTC) from macromolecules. This study aimed to evaluate the feasibility of variable delay multipulse (VDMP) CEST to separately assess solute pools with different chemical exchange rates in the human brain in vivo, while mitigating the MTC.METHODS: VDMP saturation buildup curves were simulated for amines, amides, and relayed nuclear Overhauser effect. VDMP data were acquired from glutamate and bovine serum albumin phantoms, and from six healthy volunteers at 7T. For the in vivo data, MTC removal was performed via a three-pool Lorentzian fitting. Different B1 amplitudes and mixing times were used to evaluate CEST pools with different exchange rates.RESULTS: The results show the importance of removing MTC when applying VDMP in vivo and the influence of B1 for distinguishing different pools. Finally, the optimal B1 and mixing times to effectively saturate slow- and fast-exchanging components are also reported. Slow-exchanging amides and rNOE components could be distinguished when using B1 = 1 μT and tmix = 10 ms and 40 ms, respectively. Fast-exchanging components reached the highest saturation when using a B1 = 2.8 μT and tmix = 0 ms.CONCLUSION: VDMP is a powerful CEST-editing tool, exploiting chemical exchange-rate differences. After MTC removal, it allows separate assessment of slow- and fast-exchanging solute pools in in vivo human brain.
AB - PURPOSE: Current challenges of in vivo CEST imaging include overlapping signals from different pools. The overlap arises from closely resonating pools and/or the broad magnetization transfer contrast (MTC) from macromolecules. This study aimed to evaluate the feasibility of variable delay multipulse (VDMP) CEST to separately assess solute pools with different chemical exchange rates in the human brain in vivo, while mitigating the MTC.METHODS: VDMP saturation buildup curves were simulated for amines, amides, and relayed nuclear Overhauser effect. VDMP data were acquired from glutamate and bovine serum albumin phantoms, and from six healthy volunteers at 7T. For the in vivo data, MTC removal was performed via a three-pool Lorentzian fitting. Different B1 amplitudes and mixing times were used to evaluate CEST pools with different exchange rates.RESULTS: The results show the importance of removing MTC when applying VDMP in vivo and the influence of B1 for distinguishing different pools. Finally, the optimal B1 and mixing times to effectively saturate slow- and fast-exchanging components are also reported. Slow-exchanging amides and rNOE components could be distinguished when using B1 = 1 μT and tmix = 10 ms and 40 ms, respectively. Fast-exchanging components reached the highest saturation when using a B1 = 2.8 μT and tmix = 0 ms.CONCLUSION: VDMP is a powerful CEST-editing tool, exploiting chemical exchange-rate differences. After MTC removal, it allows separate assessment of slow- and fast-exchanging solute pools in in vivo human brain.
KW - 7T
KW - chemical exchange saturation transfer (CEST)
KW - ultrahigh field
KW - variable delay multipulse (VDMP)-CEST
UR - http://www.scopus.com/inward/record.url?scp=85114769054&partnerID=8YFLogxK
U2 - 10.1002/mrm.29005
DO - 10.1002/mrm.29005
M3 - Article
C2 - 34520077
SN - 0740-3194
VL - 87
SP - 872
EP - 883
JO - Magnetic Resonance in Medicine
JF - Magnetic Resonance in Medicine
IS - 2
ER -