Projekt per år
Sammanfattning
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.
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.
Originalspråk | engelska |
---|---|
Sidor (från-till) | 1385-1400 |
Antal sidor | 16 |
Tidskrift | Magnetic Resonance in Medicine |
Volym | 89 |
Nummer | 4 |
Tidigt onlinedatum | 2022 nov. 14 |
DOI | |
Status | Published - 2023 apr. |
Ämnesklassifikation (UKÄ)
- Medicinsk bildbehandling
Fingeravtryck
Utforska forskningsämnen för ”Correction of magnetization transfer saturation maps optimized for 7T postmortem MRI of the brain”. Tillsammans bildar de ett unikt fingeravtryck.Projekt
- 1 Avslutade
-
Gradient echo-based quantitative MRI of human brain at 7T
Olsson, H. (Forskare), Andersen, M. (Biträdande handledare), Wirestam, R. (Biträdande handledare) & Helms, G. (Handledare)
2016/11/01 → 2021/10/29
Projekt: Avhandling