Demonstration of fast multi-slice quasi-steady-state chemical exchange saturation transfer (QUASS CEST) human brain imaging at 3T

• Type of Material: Article
• Authors: Hahnsung Kim, Emory University; Lisa Krishnamurthy, Emory University; Phillip Zhe Sun, Emory University
• Language: English
• Date: 2021-09-30
• Publisher: WILEY
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2021 International Society for Magnetic Resonance in Medicine.
• Final Published Version (URL): http://dx.doi.org/10.1002/mrm.29028
• Title of Journal or Parent Work: MAGNETIC RESONANCE IN MEDICINE
• Volume: 87
• Issue: 2
• Start Page: 810
• End Page: 819
• Keywords: OPTIMIZATION; multi-slice; quasi-steady-state (QUASS) CEST; AMIDE PROTON-TRANSFER; ISCHEMIC PENUMBRA; SENSITIVITY; GLIOMA; RELAXATION; chemical exchange saturation transfer (CEST); PH-WEIGHTED MRI; AGENTS; TIME; Science & Technology; Radiology, Nuclear Medicine & Medical Imaging; Life Sciences & Biomedicine; PULSED CEST

Abstract

Purpose: To combine multi-slice chemical exchange saturation transfer (CEST) imaging with quasi-steady-state (QUASS) processing and demonstrate the feasibility of fast QUASS CEST MRI at 3T. Methods: Fast multi-slice echo planar imaging (EPI) CEST imaging was developed with concatenated slice acquisition after single radiofrequency irradiation. The multi-slice CEST signal evolution was described by the spin-lock relaxation during saturation duration (Ts) and longitudinal relaxation during the relaxation delay time (Td) and post-label delay (PLD), from which the QUASS CEST was generalized to fast multi-slice acquisition. In addition, numerical simulations, phantom, and normal human subjects scans were performed to compare the conventional apparent and QUASS CEST measurements with different Ts, Td, and PLD. Results: The numerical simulation showed that the apparent CEST effect strongly depends on Ts, Td, and PLD, while the QUASS CEST algorithm minimizes such dependences. In the L-carnosine gel phantom, the proposed QUASS CEST effects (2.68 ± 0.12% [mean ± SD]) were higher than the apparent CEST effects (1.85 ± 0.26%, p < 5e-4). In the human brain imaging, Bland-Altman analysis bias of the proposed QUASS CEST effects was much smaller than the PLD-corrected apparent CEST effects (0.03% vs. −0.54%), indicating the proposed fast multi-slice CEST imaging is robust and accurate. Conclusions: The QUASS processing enables fast multi-slice CEST imaging with minimal loss in the measurement of the CEST effect.