Xiao-Yong Zhang1, Yuting Zhai1, Ziyi Jin2,3, Cong Li2,3, Phillip Zhe Sun4,5, Yin Wu6. 1. Institute of Science and Technology for Brain-Inspired Intelligence, Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Ministry of Education, Fudan University, Shanghai, China. 2. Key Laboratory of Smart Drug Delivery, Ministry of Education, School of Pharmacy, Fudan University, Shanghai, China. 3. Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China. 4. Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, USA. 5. Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA. 6. Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China.
Abstract
PURPOSE: Chemical exchange saturation transfer (CEST) MRI is versatile for measuring the dilute labile protons and microenvironment properties. However, the use of insufficiently long RF saturation duration (Ts) and relaxation delay (Td) may underestimate the CEST measurement. This study proposed a quasi-steady-state (QUASS) CEST analysis for robust CEST quantification. METHODS: The CEST signal evolution was modeled as a function of the longitudinal relaxation rate during Td and spin-lock relaxation rate during Ts, from which the QUASS-CEST effect is derived. Numerical simulation and in vivo rat glioma MRI experiments were conducted at 11.7 T to compare the apparent and QUASS-CEST results obtained under different Ts/Td of 2 seconds/2 seconds and 4 seconds/4 seconds. Magnetization transfer and amide proton transfer effects were resolved using a multipool Lorentzian fitting and evaluated in contralateral normal tissue and tumor regions. RESULTS: The simulation showed the dependence of the apparent CEST effect on Ts and Td, and such reliance was mitigated with the QUASS algorithm. Animal experiment results showed that the apparent magnetization transfer and amide proton transfer effects and their contrast between contralateral normal tissue and tumor regions increased substantially with Ts and Td. In comparison, the QUASS magnetization transfer and amide proton transfer effects and their difference between contralateral normal tissue and tumor exhibited little dependence on Ts and Td. In addition, the apparent magnetization transfer and amide proton transfer were significantly smaller than the corresponding QUASS indices (P < .05). CONCLUSION: The QUASS-CEST algorithm enables robust CEST quantification and offers a straightforward approach to standardize CEST experiments.
PURPOSE: Chemical exchange saturation transfer (CEST) MRI is versatile for measuring the dilute labile protons and microenvironment properties. However, the use of insufficiently long RF saturation duration (Ts) and relaxation delay (Td) may underestimate the CEST measurement. This study proposed a quasi-steady-state (QUASS) CEST analysis for robust CEST quantification. METHODS: The CEST signal evolution was modeled as a function of the longitudinal relaxation rate during Td and spin-lock relaxation rate during Ts, from which the QUASS-CEST effect is derived. Numerical simulation and in vivo ratglioma MRI experiments were conducted at 11.7 T to compare the apparent and QUASS-CEST results obtained under different Ts/Td of 2 seconds/2 seconds and 4 seconds/4 seconds. Magnetization transfer and amide proton transfer effects were resolved using a multipool Lorentzian fitting and evaluated in contralateral normal tissue and tumor regions. RESULTS: The simulation showed the dependence of the apparent CEST effect on Ts and Td, and such reliance was mitigated with the QUASS algorithm. Animal experiment results showed that the apparent magnetization transfer and amide proton transfer effects and their contrast between contralateral normal tissue and tumor regions increased substantially with Ts and Td. In comparison, the QUASS magnetization transfer and amide proton transfer effects and their difference between contralateral normal tissue and tumor exhibited little dependence on Ts and Td. In addition, the apparent magnetization transfer and amide proton transfer were significantly smaller than the corresponding QUASS indices (P < .05). CONCLUSION: The QUASS-CEST algorithm enables robust CEST quantification and offers a straightforward approach to standardize CEST experiments.
Authors: Jinyuan Zhou; Moritz Zaiss; Linda Knutsson; Phillip Zhe Sun; Sung Soo Ahn; Silvio Aime; Peter Bachert; Jaishri O Blakeley; Kejia Cai; Michael A Chappell; Min Chen; Daniel F Gochberg; Steffen Goerke; Hye-Young Heo; Shanshan Jiang; Tao Jin; Seong-Gi Kim; John Laterra; Daniel Paech; Mark D Pagel; Ji Eun Park; Ravinder Reddy; Akihiko Sakata; Sabine Sartoretti-Schefer; A Dean Sherry; Seth A Smith; Greg J Stanisz; Pia C Sundgren; Osamu Togao; Moriel Vandsburger; Zhibo Wen; Yin Wu; Yi Zhang; Wenzhen Zhu; Zhongliang Zu; Peter C M van Zijl Journal: Magn Reson Med Date: 2022-04-22 Impact factor: 3.737