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Updated: Mar 24, 2026
In vivo Imaging of Optic Nerve Fiber Integrity by Contrast-Enhanced MRI in Mice
Published on: July 22, 2014
Semiquantitative assessment of optic nerve injury using manganese-enhanced MRI
Jun Yang1, Qinqing Li1, Mary Wang1
1Department of Radiology, The Third Affiliated Hospital of Kunming Medical University, Yunnan Tumor Hospital, No. 519 Kunzhou Road, Xishan District, Kunming, 650118, Yunnan, People's Republic of China.
Objective:
To evaluate the capability of manganese (Mn(2+))-enhanced MRI (MEMRI) in a continuously semiquantitative assessment of rat optic nerve (ON) injury.
Methods:
Forty rats were divided into three groups: (I) a control group that was submitted to MEMRI or to fluorescent labeling of retinal ganglion cells (RGCs) (n = 10); (II) an ON injury group that was submitted to MEMRI (n = 15); (III) an ON injury group that was submitted to fluorescent labeling of RGCs (n = 15). Groups II and III were examined at 3, 7, and 14 days post-lesion (dpl), when the contrast-to-noise ratio (CNR) of the retina and ON was measured on MEMRI images and the RGCs were counted by fluorescence microscopy and compared between the groups.
Results:
In the control group, the intact visual pathway from the retina to the contralateral superior colliculus was visualized by MEMRI. In group II, continuous Mn(2+) enhancement was seen from the retina to the lesion site of the optic nerves at 3, 7, and 14 dpl. However, no Mn(2+) enhancement was observed distal to the lesion site at those time points. The observed Mn(2+) enhancement proximal to the ON lesion site declined between 7 and 14 dpl. The decrease in Mn(2+)-enhanced signal intensity at these sites at 7 and 14 dpl when compared to that at 3 dpl was significant (P < 0.05). The RGC density dropped by 6.84, 45.31, and 72.36 % at 3, 7, and 14 dpl, respectively.
Conclusion:
MEMRI can be used to evaluate the structural changes after optic nerve injury.
Insights
Manganese-enhanced MRI (MEMRI) effectively tracks optic nerve (ON) injury in rats by visualizing Mn(2+) transport. This technique shows declining signal intensity proximal to the lesion over time, correlating with retinal ganglion cell loss.
Area of Science:
- Neuroscience
- Medical Imaging
- Ophthalmology
Background:
- Optic nerve (ON) injury can lead to irreversible vision loss.
- Accurate assessment of ON injury is crucial for understanding disease progression and developing treatments.
- Current methods for evaluating ON injury may have limitations in continuous semiquantitative assessment.
Purpose of the Study:
- To evaluate the capability of manganese (Mn(2+))-enhanced MRI (MEMRI) for continuous semiquantitative assessment of rat ON injury.
- To compare MEMRI findings with direct measurements of retinal ganglion cell (RGC) loss.
Main Methods:
- Forty rats were divided into control, ON injury with MEMRI, and ON injury with RGC fluorescent labeling groups.
- MEMRI and RGC counting were performed at 3, 7, and 14 days post-lesion (dpl).
- Contrast-to-noise ratio (CNR) of the retina and ON was measured on MEMRI images.
Main Results:
- MEMRI visualized the intact visual pathway in control rats.
- In ON-injured rats, Mn(2+) enhancement was observed from the retina to the lesion site but not distal to it.
- Mn(2+) enhancement proximal to the lesion site significantly declined between 7 and 14 dpl, correlating with RGC density reduction.
Conclusions:
- MEMRI provides a valuable tool for evaluating structural changes and disease progression after ON injury.
- The semiquantitative nature of MEMRI allows for continuous monitoring of ON injury.
- MEMRI findings correlate with RGC loss, supporting its utility in preclinical ON injury studies.
