Fast and equilibrium CEST imaging of brain tumor patients at 3T

• Type of Material: Article
• Authors: Yin Wu, Chinese Academy of Sciences; Zhou Liu, Emory University; Qian Yang, Chinese Academy of Medical Sciences and Peking Union Medical College; Liyan Zou, Chinese Academy of Medical Sciences and Peking Union Medical College; Fan Zhang, Emory University; Long Qian, MR Research, GE Healthcare; Xin Liu, Chinese Academy of Sciences; Hairong Zheng, Chinese Academy of Sciences; Dehong Luo, Chinese Academy of Medical Sciences and Peking Union Medical College; Phillip Zhe Sun, Emory University
• Language: English
• Date: 2021-12-02
• Publisher: ELSEVIER SCI LTD
• Publication Version: Final Published Version
• Copyright Statement: © 2021 Published by Elsevier Inc.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.nicl.2021.102890
• Title of Journal or Parent Work: NEUROIMAGE-CLINICAL
• Volume: 33
• Start Page: 102890
• End Page: 102890
• Grant/Funding Information: National Natural Science Foundation of China (81871348 and 91859102 to Y.W.) and the Key Areas Research and Development Program of Guangdong (2019B020235001 to Y.W.).
• Keywords: Neuroimaging; Chemical exchange saturation transfer; Neurosciences & Neurology; MAGNETIZATION-TRANSFER; MR SPECTROSCOPY; Tumor; PROTEINS; EXCHANGE; DIFFERENTIATION; OPTIMIZATION; Science & Technology; Life Sciences & Biomedicine; AMIDE PROTON-TRANSFER; WATER SATURATION; DIFFUSE GLIOMAS; RELAXATION; Amide proton transfer; Quasi-steady-state (QUASS)
• Research Categories: Health Sciences, Radiology; Health Sciences, Medicine and Surgery

Abstract

Chemical exchange saturation transfer (CEST) MRI, versatile for detecting endogenous mobile proteins and tissue pH, has proved valuable in tumor imaging. However, CEST MRI scans are often performed under non-equilibrium conditions, which confound tissue characterization. This study proposed a quasi-steady-state (QUASS) CEST MRI algorithm to standardize fast and accurate tumor imaging at 3 T. The CEST signal evolution was modeled by longitudinal relaxation rate during relaxation delay (Td) and spinlock relaxation during RF saturation time (Ts), from which the QUASS CEST effect is derived. Numerical simulation and human MR imaging experiments (7 healthy volunteers and 19 tumor patients) were conducted at 3 T to compare the CEST measurements obtained under two representative experimental conditions. In addition, amide proton transfer (APT), combined magnetization transfer (MT) and nuclear overhauser enhancement (NOE) effects, and direct water saturation were isolated using a 3-pool Lorentzian fitting in white matter and gray matter of healthy volunteers and for patients in the contralateral normal-appearing white matter and tumor regions. Finally, the student's t-test was performed between conventional and QUASS CEST measurements. The routine APT and combined MT & NOE measures significantly varied with Ts and Td (P < .001) and were significantly smaller than the corresponding QUASS indices (P < .001). In contrast, the results from the QUASS reconstruction showed little dependence on the scan protocol (P > .05), indicating the accuracy and robustness of QUASS CEST MRI for tumor imaging. To summarize, the QUASS CEST reconstruction algorithm enables fast and accurate tumor CEST imaging at 3 T, promising to expedite and standardize clinical CEST MRI.