Magnetic Resonance Imaging and Spectroscopy of the Rat Hippocampus 1 Month after Exposure to 56Fe-Particle Radiation

Obenaus, A., Huang, L., Smith, A., Favre, C. J., Nelson, G. and Kendall, E. Magnetic Resonance Imaging and Spectroscopy of the Rat Hippocampus 1 Month after Exposure to 56Fe-Particle Radiation. Radiat. Res. 169, 149–161 (2008). The response of the central nervous system to space radiation is largely...

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Published in:Radiation research 2008-02, Vol.169 (2), p.149-161
Main Authors: Obenaus, A., Huang, L., Smith, A., Favre, C. J., Nelson, G., Kendall, E.
Format: Article
Language:English
Subjects:
Animals
Aspartic Acid - analogs & derivatives
Aspartic Acid - metabolism
Choline - metabolism
Cosmic Radiation
Dose-Response Relationship, Radiation
Environmental Exposure
Hippocampus - anatomy & histology
Hippocampus - physiology
Hippocampus - radiation effects
Iron Isotopes
Magnetic Resonance Imaging
Magnetic Resonance Spectroscopy
Male
Radiation Dosage
Rats
Rats, Sprague-Dawley
Regular s
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Summary:Obenaus, A., Huang, L., Smith, A., Favre, C. J., Nelson, G. and Kendall, E. Magnetic Resonance Imaging and Spectroscopy of the Rat Hippocampus 1 Month after Exposure to 56Fe-Particle Radiation. Radiat. Res. 169, 149–161 (2008). The response of the central nervous system to space radiation is largely unknown. The hippocampus, which is known for its critical role in learning and memory, was evaluated for its response to heavy-ion radiation. At 1 month, animals exposed to brain-only 56Fe-particle irradiation (0–4 Gy) were examined using contrast-enhanced T1 imaging (CET1), T2-weighted imaging (T2WI), diffusion weighted imaging (DWI), and 1H-magnetic resonance spectroscopy (MRS). Correlative histology was performed after imaging. The T2WI, DWI and CET1 images revealed no overt anatomical changes after irradiation. Quantitative analysis demonstrated a significant increase in T2 at 2 Gy compared to 0 Gy. The apparent diffusion coefficient (ADC) revealed an inverse dose-dependent quantitative change in water mobility. Compared to 0 Gy, the ADC increased 122% at 1 Gy and declined to 44% above control levels at 4 Gy. MRS showed a significant increase in the N-acetylaspartate/choline ratio at 4 Gy and a lactate peak. Histology demonstrated no overt pathological changes in neuronal and astrocyte populations. However, a significant inverse dose-dependent morphological change in the microglial population was detected in irradiated animals. Our results suggest that early tissue matrix modifications induced by 56Fe-particle radiation can be detected by MRI in the absence of evident histopathology. These changes may indicate fundamental changes in the structure and function of the hippocampus.
ISSN:0033-7587
1938-5404
DOI:10.1667/RR1135.1