Correction of magnetization transfer saturation maps optimized for 7T postmortem MRI of the brain
Lipp, Ilona ; Kirilina, Evgeniya ; Edwards, Luke J. ; Pine, Kerrin J. ; Jäger, Carsten ; Grässle, Tobias ; Weiskopf, Nikolaus and Helms, Gunther LU
(2023)
In Magnetic Resonance in Medicine
89(4).
p.1385-1400
- Abstract
- Purpose
Magnetization transfer saturation (MTsat) is a useful marker to probe tissue macromolecular content and myelination in the brain. The increased B1+ inhomogeneity at 7T and significantly larger saturation pulse flip angles which are often used for postmortem studies exceed the limits where previous B1+
correction methods are applicable. Here, we develop a calibration-based correction model and procedure, and validate and evaluate it in postmortem 7T data of whole chimpanzee brains.
Theory
The B1+ dependence of was investigated by varying the off-resonance saturation pulse flip angle. For the range of saturation pulse flip angles applied in typical experiments on postmortem tissue, the dependence was close to... (More) - Purpose
Magnetization transfer saturation (MTsat) is a useful marker to probe tissue macromolecular content and myelination in the brain. The increased B1+ inhomogeneity at 7T and significantly larger saturation pulse flip angles which are often used for postmortem studies exceed the limits where previous B1+
correction methods are applicable. Here, we develop a calibration-based correction model and procedure, and validate and evaluate it in postmortem 7T data of whole chimpanzee brains.
Theory
The B1+ dependence of was investigated by varying the off-resonance saturation pulse flip angle. For the range of saturation pulse flip angles applied in typical experiments on postmortem tissue, the dependence was close to linear. A linear model with a single calibration constant C is proposed to correct bias in MTsat by mapping it to the reference value of the saturation pulse flip angle.
Methods
MTsat was estimated voxel-wise in five postmortem chimpanzee brains. “Individual-based global parameters” were obtained by calculating the mean
C within individual specimen brains and “group-based global parameters” by calculating the means of the individual-based global parameters across the five brains.
Results
The linear calibration model described the data well, though C was not entirely independent of the underlying tissue and B1+. Individual-based correction parameters and a group-based global correction parameter (C=1.2) led to visible, quantifiable reductions of B1+-biases in high-resolution MTsat maps.
Conclusion
The presented model and calibration approach effectively corrects for B1+
inhomogeneities in postmortem 7T data. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/40b302f4-8eb8-4f1a-baae-67a317d0a5f7
- author
- Lipp, Ilona
; Kirilina, Evgeniya
; Edwards, Luke J.
; Pine, Kerrin J.
; Jäger, Carsten
; Grässle, Tobias
; Weiskopf, Nikolaus
and Helms, Gunther
LU
- contributor
- EBC Consortium
- organization
- publishing date
- 2023-04
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Magnetic Resonance in Medicine
- volume
- 89
- issue
- 4
- pages
- 16 pages
- publisher
- John Wiley & Sons Inc.
- external identifiers
-
- pmid:36373175
- scopus:85142282546
- ISSN
- 1522-2594
- DOI
- 10.1002/mrm.29524
- project
- Gradient echo-based quantitative MRI of human brain at 7T
- language
- English
- LU publication?
- yes
- id
- 40b302f4-8eb8-4f1a-baae-67a317d0a5f7
- date added to LUP
- 2022-11-14 15:15:52
- date last changed
- 2023-01-30 15:26:26
@article{40b302f4-8eb8-4f1a-baae-67a317d0a5f7,
abstract = {{Purpose<br/>Magnetization transfer saturation (MTsat) is a useful marker to probe tissue macromolecular content and myelination in the brain. The increased B1+ inhomogeneity at 7T and significantly larger saturation pulse flip angles which are often used for postmortem studies exceed the limits where previous B1+<br/>correction methods are applicable. Here, we develop a calibration-based correction model and procedure, and validate and evaluate it in postmortem 7T data of whole chimpanzee brains.<br/><br/>Theory<br/>The B1+ dependence of was investigated by varying the off-resonance saturation pulse flip angle. For the range of saturation pulse flip angles applied in typical experiments on postmortem tissue, the dependence was close to linear. A linear model with a single calibration constant C is proposed to correct bias in MTsat by mapping it to the reference value of the saturation pulse flip angle.<br/><br/>Methods<br/>MTsat was estimated voxel-wise in five postmortem chimpanzee brains. “Individual-based global parameters” were obtained by calculating the mean<br/>C within individual specimen brains and “group-based global parameters” by calculating the means of the individual-based global parameters across the five brains.<br/><br/>Results<br/>The linear calibration model described the data well, though C was not entirely independent of the underlying tissue and B1+. Individual-based correction parameters and a group-based global correction parameter (C=1.2) led to visible, quantifiable reductions of B1+-biases in high-resolution MTsat maps.<br/><br/>Conclusion<br/>The presented model and calibration approach effectively corrects for B1+<br/>inhomogeneities in postmortem 7T data.}},
author = {{Lipp, Ilona and Kirilina, Evgeniya and Edwards, Luke J. and Pine, Kerrin J. and Jäger, Carsten and Grässle, Tobias and Weiskopf, Nikolaus and Helms, Gunther}},
issn = {{1522-2594}},
language = {{eng}},
number = {{4}},
pages = {{1385--1400}},
publisher = {{John Wiley & Sons Inc.}},
series = {{Magnetic Resonance in Medicine}},
title = {{Correction of magnetization transfer saturation maps optimized for 7T postmortem MRI of the brain}},
url = {{http://dx.doi.org/10.1002/mrm.29524}},
doi = {{10.1002/mrm.29524}},
volume = {{89}},
year = {{2023}},
}