Removal of cerebrospinal fluid partial volume effects in quantitative magnetization transfer imaging using a three‐pool model with nonexchanging water component. Issue 5 (13th November 2014)

• Record Type: Journal Article
• Authors: Mossahebi, Pouria; Alexander, Andrew L.; Field, Aaron S.; Samsonov, Alexey A.
• Is Part Of: Magnetic resonance in medicine. Volume 74:Issue 5(2015:Nov.)
• Page Start: 1317
• Page End: 1326
• Publication Date: 2014-11-13
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.25516
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm25516-sec-0001" sec-type="section"> <title>Purpose</title> <p>Parameters of the two‐pool model describing magnetization transfer (MT) in macromolecule‐rich tissues may be significantly biased in partial volume (PV) voxels containing cerebrospinal fluid (CSF). The purpose of this study was to develop a quantitative MT (qMT) method that provides indices insensitive to CSF PV averaging.</p> </sec> <sec id="mrm25516-sec-0002" sec-type="section"> <title>Theory and Methods</title> <p>We propose a three‐pool MT model, in which PV macro‐compartment is modeled as an additional nonexchanging water pool. We demonstrate the feasibility of model parameter estimation from several MT‐weighted spoiled gradient echo datasets. We validated the three‐pool model in numerical, phantom, and in vivo studies.</p> </sec> <sec id="mrm25516-sec-0003" sec-type="section"> <title>Results</title> <p>PV averaging with the free water compartment reduces all qMT parameters, most significantly affecting macromolecular proton fraction (MPF) and cross‐relaxation rate. Monte‐Carlo simulations confirmed stability of the three‐pool model fit. Unlike the standard two‐pool model, the three‐pool model qMT parameters were not affected by PV averaging in simulations and phantom studies. The three‐pool model fit allowed CSF PV correction in brain PV voxels and resulted in good correlation with standard two‐pool model parameters in non‐PV voxels.</p> </sec> <sec id="mrm25516-sec-0004" sec-type="section"> <title>Conclusion</title> <p>Quantitative MT imaging based on a three‐pool model with a non‐exchanging water component yields a set of CSF‐insensitive qMT parameters, which may improve MPF‐based assessment of myelination in structures strongly affected by CSF PV averaging such as brain gray matter. Magn Reson Med 74:1317–1326, 2015. © 2014 Wiley Periodicals, Inc.</p> </sec> </abstract>