Unbiased signal equation for quantitative magnetization transfer mapping in balanced steady‐state free precession MRI

Abstract: Purpose
Quantitative magnetization transfer (qMT) imaging can be used to quantify the proportion of protons in a voxel attached to macromolecules. Here, we show that the original qMT balanced steady-state free precession (bSSFP) model is biased due to over-simplistic assumptions made in its derivation.

Theory and Methods
We present an improved model for qMT bSSFP, which incorporates finite radiofrequency (RF) pulse effects as well as simultaneous exchange and relaxation. Furthermore, a correction relating to finite RF pulse effects for sinc-shaped excitations is derived. The new model is compared to the original one in numerical simulations of the Bloch-McConnell equations and in previously acquired in vivo data.

Results
Our numerical simulations show that the original signal equation is significantly biased in typical brain tissue structures (by 7%-20%), whereas the new signal equation outperforms the original one with minimal bias (<1%). It is further shown that the bias of the original model strongly affects the acquired qMT parameters in human brain structures, with differences in the clinically relevant parameter of pool-size-ratio of up to 31%. Particularly high biases of the original signal equation are expected in an MS lesion within diseased brain tissue (due to a low T2/T1-ratio), demanding a more accurate model for clinical applications.

Conclusion
The improved model for qMT bSSFP is recommended for accurate qMT parameter mapping in healthy and diseased brain tissue structures

Standort
Deutsche Nationalbibliothek Frankfurt am Main
Umfang
Online-Ressource
Sprache
Englisch
Anmerkungen
Magnetic resonance in medicine. - 87, 1 (2022) , 446-456, ISSN: 1522-2594

Ereignis
Veröffentlichung
(wo)
Freiburg
(wer)
Universität
(wann)
2023
Urheber
Bayer, Fritz M.
Bock, Michael
Jezzard, Peter
Smith, Alex K.

DOI
10.1002/mrm.28940
URN
urn:nbn:de:bsz:25-freidok-2197644
Rechteinformation
Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
Letzte Aktualisierung
25.03.2025, 13:41 MEZ

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Beteiligte

  • Bayer, Fritz M.
  • Bock, Michael
  • Jezzard, Peter
  • Smith, Alex K.
  • Universität

Entstanden

  • 2023

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