Powell, Elizabeth;
Ohene, Yolanda;
Battiston, Marco;
Dickie, Ben R;
Parkes, Laura M;
Parker, Geoff JM;
(2023)
Blood-brain barrier water exchange measurements using FEXI: Impact of modeling paradigm and relaxation time effects.
Magnetic Resonance in Medicine
10.1002/mrm.29616.
(In press).
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Abstract
PURPOSE: To evaluate potential modeling paradigms and the impact of relaxation time effects on human blood-brain barrier (BBB) water exchange measurements using FEXI (BBB-FEXI), and to quantify the accuracy, precision, and repeatability of BBB-FEXI exchange rate estimates at 3 T. METHODS: Three modeling paradigms were evaluated: (i) the apparent exchange rate (AXR) model; (ii) a two-compartment model (2CM) explicitly representing intra- and extravascular signal components, and (iii) a two-compartment model additionally accounting for finite compartmental T1 and T2 relaxation times (2CMr). Each model had three free parameters. Simulations quantified biases introduced by the assumption of infinite relaxation times in the AXR and 2CM models, as well as the accuracy and precision of all three models. The scan–rescan repeatability of all paradigms was quantified for the first time in vivo in 10 healthy volunteers (age range 23–52 years; five female) RESULTS: The assumption of infinite relaxation times yielded exchange rate errors in simulations up to 42%/14% in the AXR/2CM models, respectively. Accuracy was highest in the compartmental models; precision was best in the AXR model. Scan–rescan repeatability in vivo was good for all models, with negligible bias and repeatability coefficients in grey matter of RCAXR = 0.43 s −1, RC2CM = 0.51 s −1, and RC2CMr = 0.61 s −1. CONCLUSION: Compartmental modelling of BBB-FEXI signals can provide accurate and repeatable measurements of BBB water exchange; however, relaxation time and partial volume effects may cause model-dependent biases.
| Type: | Article |
|---|---|
| Title: | Blood-brain barrier water exchange measurements using FEXI: Impact of modeling paradigm and relaxation time effects |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1002/mrm.29616 |
| Publisher version: | https://doi.org/10.1002/mrm.29616 |
| Language: | English |
| Additional information: | © 2023 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
| Keywords: | FEXI, blood-brain barrier, diffusion MRI, permeability, water exchange |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10167002 |
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