Low-intensity rim on T2-weighted brainstem imaging: a universally observed structure exhibiting a negative magnetic
Ryo Yamakuni1, Hironobu Ishikawa2, Shiro Ishii3
1Department of Radiology and Nuclear Medicine, Fukushima Medical University School of Medicine, 1Hikariga-Oka, Fukushima City, Fukushima, 960-1295, Japan. yamakuni@fmu.ac.jp.
Purpose:
In healthy participants, T2 physiological rim (T2-PR) similar to superficial siderosis has been observed in the brainstem. This study aimed to determine the incidence and causes of T2-PR.
Materials And Methods:
To determine the incidence, T2-weighted imaging (T2WI) was performed on 106 patients (65 males; mean age: 62.5 years) using a 3.0-T scanner and visually assessed by two radiologists. T2-PR presence in 22 brain areas was evaluated using the following system: 0 for absence, 1 for < 50% surface, 2 for ≥ 50% but not the entirety, and 3 for the entirety. After assessing inter-rater agreement, the scores were averaged. To investigate the causes of T2-PR, an experimental MR imaging (MRI) was performed on a healthy volunteer. To evaluate the chemical shift effect, the bandwidth and encoding direction were modified. To assess the magnetic susceptibility effect, χ-separation analysis and T2WI/T2*WI was performed using varying echo times (TEs).
Results:
A substantial inter-rater score agreement (κ = 0.790) was observed. T2-PR was identified in all participants and was most frequently observed on the frontal and lateral sides of the midbrain and pons, with the highest occurrence on the frontal of the upper pons (median 2.0; interquartile range 2.0-3.0). In the experimental MRI, no differences in T2-PR were observed across the varying bandwidths and encoding directions. The low signal for T2WI/T2*WI thickened as the TE lengthened. Moreover, χ-separation analysis revealed diamagnetic susceptibility properties in the region where T2-PR was observed.
Conclusion:
T2-PR can be observed in the midbrain and pons. Both these areas exhibit the diamagnetic susceptible properties.
Insights
T2 physiological rim (T2-PR) is a common finding in the brainstem of healthy individuals. This study found T2-PR in all participants, revealing diamagnetic susceptibility in the midbrain and pons.
Area of Science:
- Neuroimaging
- Radiology
- Biophysics
Background:
- T2 physiological rim (T2-PR), resembling superficial siderosis, is observed in the brainstem of healthy individuals.
- The incidence and underlying causes of T2-PR require further investigation.
Purpose of the Study:
- To determine the incidence of T2-PR in a cohort of healthy participants.
- To investigate the potential causes of T2-PR, focusing on magnetic susceptibility effects.
Main Methods:
- 106 healthy participants underwent 3.0-T T2-weighted imaging (T2WI) to assess T2-PR incidence across 22 brain areas.
- Experimental MRI on a healthy volunteer evaluated chemical shift and magnetic susceptibility effects by altering imaging parameters.
- T2WI/T2*WI with varying echo times and chi-separation analysis were used to assess magnetic susceptibility.
Main Results:
- High inter-rater agreement (κ=0.790) was achieved in T2-PR assessment.
- T2-PR was present in all participants, predominantly on the frontal and lateral aspects of the midbrain and pons.
- Experimental MRI indicated diamagnetic susceptibility properties in T2-PR regions, with no dependence on bandwidth or encoding direction.
Conclusions:
- T2-PR is a consistent finding in the midbrain and pons of healthy individuals.
- The observed T2-PR is associated with diamagnetic susceptibility in these brainstem regions.
Related Concept Videos
01:24Magnetic Resonance Imaging
01:27Imaging Studies IV: Magnetic Resonance Imaging
01:21Imaging Studies for Cardiovascular System IV: CMRI
01:14Brain Imaging
These technologies include computerized axial tomography (CAT or CT scans), positron-emission tomography (PET scans), magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), and Transcranial Magnetic...