Quantitative assessment of central nervous system disorder induced by prenatal X-ray exposure using diffusion and manganese-enhanced MRI
✍ Scribed by Shigeyoshi Saito; Ichio Aoki; Kazuhiko Sawada; Tetsuya Suhara
- Book ID
- 102957764
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 855 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0952-3480
- DOI
- 10.1002/nbm.1715
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✦ Synopsis
Prenatal radiation exposure induces various central nervous system (CNS) disorders depending on the dose, affected region and gestation period. The goal of this study was to assess noninvasively a CNS development disorder induced by prenatal X-ray exposure using quantitative manganese-enhanced MRI (MEMRI) as well as apparent diffusion coefficient (ADC) and transverse relaxation time (T 2 ) maps in comparison with immunohistological staining. The changes in ΔR 1 (increase in the longitudinal relaxation rate (R 1 ) from before and after MnCl 2 administration.) induced by the Mn 2+ contrast agent were evaluated in the CNS of normal and prenatally irradiated rats. ADC and T 2 were also compared with the histological results obtained using hematoxylin and eosin (to estimate cell density), activated caspase-3 (apoptotic cells) and glial fibrillary acidic protein (proliferation of astrocytes/astroglia). We found the following: (i) the decreased Mn 2+ uptake (indicated by a smaller ΔR 1 ) for radiation-exposed rats was predominantly correlated with a decrease in cell viability (apoptotic cytopathogenicity) and CNS cell density after prenatal radiation exposure; (ii) the longer T 2 and ADC were associated with a decrease in CNS cell density and apoptotic alteration after radiation exposure. In addition to the slight proliferation of astroglia (+58%), there was a substantial decrease in cell density (-78%) and an excessive increase in apoptotic cells (+613%) in our prenatal radiation exposure model. The results suggest that MEMRI in the prenatal X-ray exposure model predominantly reflected the decrease in cell density and viability rather than the proliferation of astroglia. In conclusion, quantitative MEMRI with ADC/T 2 mapping provides objective information for the in vivo assessment of cellular level alterations by prenatal radiation exposure, and has the potential to be used as a standard approach for the evaluation of the cellular damage of radiotherapy.