Dynamic MRI of rat brain following manganese administration through the internal carotid artery

Abstract

Objective:

In this study, we investigated the dynamic distribution processes of Mn²⁺ in rat brain using magnetic resonance imaging (MRI) after an intra-arterial (IA) injection of MnCl₂ and following the breaking of the blood–brain barrier (BBB).

Methods:

Adult male Sprague-Dawley (SD) rats were employed in the study. After the rats were anesthetized with urethane, 25% mannitol was administrated into the right internal carotid artery (ICA) in order to disrupt the BBB, 50 mmol/l (10 mg/kg) of MnCl₂ was then injected into ICA prior to the MRI assay. The MRI was performed at 7 T for a continuous 2 hours following the administration of MnCl₂. Image reconstruction and analysis were performed using the Statistical Parametric Mapping (SPM) software.

Results:

As time progressed, the Mn²⁺ enhanced signal intensity showed a gradual increase with a maximum increase at 10 minutes following MnCl₂ administration, and began to decline after 10 minutes. From 30 minutes to 2 hours, the signal-enhanced region became more homogeneous, and the signal-enhanced range spread to the contralateral area up to 2 hours after MnCl₂ administration.

Conclusion:

These results will help future research to select an appropriate time point to perform functional MRI for different types of activity-induced manganese (AIM) MRI research studies. These findings will allow researchers to discriminate intended, stimulation-specific enhanced signal from unintended, nonspecific enhanced signals.

Keywords:

• Dynamic MRI
• Manganese
• Blood–brain barrier (BBB)
• Internal carotid artery (ICA)

Acknowledgements

This study was funded by the National Science Fund of China (No. 81171179,81272439, 31300921), the Funds for Key Sci-Tech Research Projects of Guangdong (No.2008A030201019) and Guangzhou (No. 09B52120112-2009J1-C418-2, No. 2008A1-E4011-6).