Direct saturation‐corrected chemical exchange saturation transfer MRI of glioma: Simplified decoupling of amide proton transfer and nuclear overhauser effect contrasts

Purpose Chemical exchange saturation transfer (CEST) MRI has shown promise in tissue characterization in diseases like stroke and tumor. However, in vivo CEST imaging such as amide proton transfer (APT) MRI is challenging because of concomitant factors such as direct water saturation, macromolecular...

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Published in:Magnetic resonance in medicine 2017-12, Vol.78 (6), p.2307-2314
Main Authors: Yuwen Zhou, Iris, Wang, Enfeng, Cheung, Jerry S., Lu, Dongshuang, Ji, Yang, Zhang, Xiaoan, Fulci, Giulia, Sun, Phillip Zhe
Format: Article
Language:English
Subjects:
Algorithms
amide proton transfer (APT)
Animals
Brain
Brain - diagnostic imaging
Brain cancer
Brain mapping
Brain Neoplasms - diagnostic imaging
Brain tumors
chemical exchange saturation transfer (CEST)
Creatine
Decoupling
direct water saturation
Glioma
Glioma - diagnostic imaging
Image Interpretation, Computer-Assisted
Image Processing, Computer-Assisted
In vivo methods and tests
Least-Squares Analysis
Macromolecules
Magnetic Resonance Imaging
Male
Neuroimaging
Nuclear Overhauser enhancement (NOE)
Overhauser effect
Phantoms, Imaging
Protons
Rats
Rats, Inbred F344
RF spillover
Saturation
Sensitivity and Specificity
Substantia alba
Substantia grisea
three‐offset method
tumor
Tumors
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Summary:Purpose Chemical exchange saturation transfer (CEST) MRI has shown promise in tissue characterization in diseases like stroke and tumor. However, in vivo CEST imaging such as amide proton transfer (APT) MRI is challenging because of concomitant factors such as direct water saturation, macromolecular magnetization transfer, and nuclear overhauser effect (NOE), which lead to a complex contrast in the commonly used asymmetry analysis (MTRasym). Here, we propose a direct saturation‐corrected CEST (DISC‐CEST) analysis for simplified decoupling and quantification of in vivo CEST effects. Methods CEST MRI and relaxation measurements were carried out on a classical 2‐pool creatine‐gel CEST phantom and normal rat brains (N = 6) and a rat model of glioma (N = 8) at 4.7T. The proposed DISC‐CEST quantification was carried out and compared with conventional MTRasym and the original three‐offset method. Results We demonstrated that the DISC‐CEST contrast in the phantom had much stronger correlation with MTRasym than the three‐offset method, which showed substantial underestimation. In normal rat brains, the DISC‐CEST approach revealed significantly stronger APT effect in gray matter and higher NOE effect in white matter. Furthermore, the APT and NOE maps derived from DISC‐CEST showed significantly higher APT effect in the tumors than contralateral normal tissue but no apparent difference in NOE. Conclusion The proposed DISC‐CEST method, by correction of nonlinear direct water saturation effect, serves as a promising alternative to both the commonly used MTRasym and the simplistic three‐offset analyses. It provides simple yet reliable in vivo CEST quantification such as APT and NOE mapping in brain tumor, which is promising for clinical translation. Magn Reson Med 78:2307–2314, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
ISSN:0740-3194
1522-2594
DOI:10.1002/mrm.26959