Purpose: Diffusion time (Δ) effect in diffusion measurements has been validated as a sensitive biomarker in liver fibrosis by rat models. To extend this finding to clinical study, a reliable imaging technique is highly desirable. This study aimed to develop an optimal stimulated echo acquisition mode (STEAM) diffusion-weighted imaging (DWI) method dedicated to human liver imaging on 3 Tesla (T) and preliminarily investigate the dependence effect in healthy volunteers.
Methods: STEAM DWI with single-shot echo planar imaging readout was used as it provided better signal-to-noise ratio (SNR) than spin echo DWI methods when a long Δ was needed for liver imaging. Additionally, a slice-selection gradient reversal method was used for fat suppression. Motion compensation and SNR improvement strategies were used to further improve the image quality. Five b-values with three Δs were tested in 10 volunteers.
Results: Effective fat suppression and motion compensation were reproducibly achieved in the optimized sequence. The signal decay generally became slower when the Δs increased. Obvious reduction of diffusion coefficients was observed with increasing Δs in the liver.
Conclusion: The results verified the Δ dependence in diffusion measurements, indicating restricted diffusion in healthy human livers for the first time at 3T. This prepared STEAM DWI a potential technique for liver fibrotic studies in clinical practice. Magn Reson Med 77:300-309, 2017. © 2016 Wiley Periodicals, Inc.
Keywords: STEAM DWI; diffusion time dependence; liver DWI; restricted diffusion.
© 2016 Wiley Periodicals, Inc.