Volume 89, Issue 5 pp. 1990-2004
RESEARCH ARTICLE
Open Access

Quantification of blood–brain barrier water exchange and permeability with multidelay diffusion-weighted pseudo-continuous arterial spin labeling

Xingfeng Shao

Corresponding Author

Xingfeng Shao

Laboratory of FMRI Technology, Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA

Correspondence

Xingfeng Shao, Laboratory of FMRI Technology, Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.

Email: [email protected]

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Chenyang Zhao

Chenyang Zhao

Laboratory of FMRI Technology, Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA

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Qinyang Shou

Qinyang Shou

Laboratory of FMRI Technology, Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA

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Keith S. St Lawrence

Keith S. St Lawrence

Lawson Health Research Institute, London, Ontario, Canada

Department of Medical Biophysics, Western University, London, Ontario, Canada

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Danny J. J. Wang

Danny J. J. Wang

Laboratory of FMRI Technology, Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, USA

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First published: 09 January 2023
Citations: 5

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Funding information: National Institute of Health (NIH), Grant/Award Numbers: R01-EB028297, R01-NS114382, UF1-NS100614

Abstract

Purpose

To present a pulse sequence and mathematical models for quantification of blood–brain barrier water exchange and permeability.

Methods

Motion-compensated diffusion-weighted (MCDW) gradient-and-spin echo (GRASE) pseudo-continuous arterial spin labeling (pCASL) sequence was proposed to acquire intravascular/extravascular perfusion signals from five postlabeling delays (PLDs, 1590–2790 ms). Experiments were performed on 11 healthy subjects at 3 T. A comprehensive set of perfusion and permeability parameters including cerebral blood flow (CBF), capillary transit time (τc), and water exchange rate (kw) were quantified, and permeability surface area product (PSw), total extraction fraction (Ew), and capillary volume (Vc) were derived simultaneously by a three-compartment single-pass approximation (SPA) model on group-averaged data. With information (i.e., Vc and τc) obtained from three-compartment SPA modeling, a simplified linear regression of logarithm (LRL) approach was proposed for individual kw quantification, and Ew and PSw can be estimated from long PLD (2490/2790 ms) signals. MCDW-pCASL was compared with a previously developed diffusion-prepared (DP) pCASL sequence, which calculates kw by a two-compartment SPA model from PLD = 1800 ms signals, to evaluate the improvements.

Results

Using three-compartment SPA modeling, group-averaged CBF = 51.5/36.8 ml/100 g/min, kw = 126.3/106.7 min−1, PSw = 151.6/93.8 ml/100 g/min, Ew = 94.7/92.2%, τc = 1409.2/1431.8 ms, and Vc = 1.2/0.9 ml/100 g in gray/white matter, respectively. Temporal SNR of MCDW-pCASL perfusion signals increased 3-fold, and individual kw maps calculated by the LRL method achieved higher spatial resolution (3.5 mm3 isotropic) as compared with DP pCASL (3.5 × 3.5 × 8 mm3).

Conclusion

MCDW-pCASL allows visualization of intravascular/extravascular ASL signals across multiple PLDs. The three-compartment SPA model provides a comprehensive measurement of blood–brain barrier water dynamics from group-averaged data, and a simplified LRL method was proposed for individual kw quantification.

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