Abstract
Magnetic resonance imaging (MRI) is now an essential tool in the field of neuroscience involving non-human primates (NHP). Structural MRI scanning using T1-weighted (T1w) or T2-weighted (T2w) images provides anatomical information, particularly for experiments involving deep structures such as the basal ganglia and cerebellum. However, for certain subcortical structures, T1w and T2w images fail to reveal important anatomical details. To better visualize such structures in the macaque brain, we applied a relatively new method called quantitative susceptibility mapping (QSM), which enhances tissue contrast based on the local tissue magnetic susceptibility. To evaluate the visualization of important structures, we quantified the the contrast-to-noise ratios (CNRs) of the ventral pallidum (VP), globus pallidus external and internal segments (GPe and GPi), substantia nigra (SN), subthalamic nucleus (STN) in the basal ganglia and the dentate nucleus (DN) in the cerebellum. For these structures, the QSM method significantly increased the CNR, and thus the visibility, beyond that in either the T1w or T2w images. In addition, QSM values of some structures were correlated to the age of the macaque subjects. These results indicate that the QSM method can enable the clear identification of certain subcortical structures that are invisible in more traditional scanning sequences.
Highlights
NHP subcortical structures are challenging to see in conventional T1w and T2w images
We applied quantitative susceptibility mapping (QSM) to identify them easily
QSM clearly visualized basal ganglia and cerebellar nucleus of high brain iron content
CNRs of some subcortical nucleus were significantly higher in QSM
QSM values of several subcortical nucleus increased with age
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Conflict of interest: All authors claim that there are no conflicts of interest.
Abbreviation
- AC
- anterior commissure
- CNR
- contrast-to-noise ratio
- CdB
- body of caudate nucleus
- CdH
- head of caudate nucleus
- CdT
- tail of caudate nucleus
- DBS
- deep brain stimulation
- DN
- dentate nucleus
- GPe
- globus pallidus external segment
- GPi
- globus pallidus internal segment
- IC
- internal capsule
- GRE
- gradient echo
- MCP
- middle cerebellar peduncle
- MPRAGE
- magnetization prepared rapid gradient echo
- MRI
- magnetic resonance imaging
- NHP
- non-human primate
- NMT
- NIMH macaque template
- OT
- optic tract
- Put
- putamen
- QSM
- quantitative susceptibility mapping
- ROI
- region of interest
- SARM
- subcortical atlas of the rhesus macaque
- SN
- substantia nigra
- SPACE
- sampling perfection with application optimized contrasts using different flip angle evolution
- STN
- subthalamic nucleus
- T1w
- T1-weighted
- T2w
- T2-weighted
- TE
- echo time
- TR
- repetition time
- 3D
- three-dimensional
- VP
- ventral pallidum