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Magnetic resonance imaging temporarily alters blood-brain barrier permeability in the rat
Abstract:
Exposure to a short (23.2 min) standard clinical magnetic resonance imaging (MRI) procedure elicits a temporary dysfunction of the blood-brain barrier in rats. Monitoring of the increased permeability of rat brain frontal cortex microvessels with the protein tracer horseradish peroxidase and freeze-fracture electron microscopy, revealed an amplified vesicle-mediated transport of tracer across the microvessel endothelium to the albuminal basal lamina and extracellular compartment of the brain parenchyma. Recovery of normal blood-brain function, as evidenced by exclusion of protein tracer from subendothelial basal lamina and neuropil extracellular milieu, was complete 15-30 min following cessation of the MRI exposure. These findings raise the possibility that exposure to clinical MRI procedures may also temporarily alter central blood-brain permeability in human subjects.
Insights
Standard clinical magnetic resonance imaging (MRI) temporarily disrupts the blood-brain barrier in rats by increasing microvessel permeability. Normal function recovers within 30 minutes post-exposure.
Area of Science:
- Neuroscience
- Biomedical Imaging
- Vascular Biology
Background:
- The blood-brain barrier (BBB) protects the central nervous system but can be compromised by external factors.
- Magnetic Resonance Imaging (MRI) is a widely used diagnostic tool, and its effects on the BBB require investigation.
Purpose of the Study:
- To investigate the impact of a standard clinical MRI procedure on the integrity of the blood-brain barrier in a rat model.
- To characterize the temporal dynamics of BBB permeability changes following MRI exposure.
Main Methods:
- Utilized a standard clinical MRI protocol (23.2 minutes) on rats.
- Assessed blood-brain barrier permeability using the protein tracer horseradish peroxidase (HRP).
- Employed freeze-fracture electron microscopy to visualize microvessel endothelium and tracer transport.
Main Results:
- MRI exposure induced temporary blood-brain barrier dysfunction in the rat frontal cortex.
- Increased vesicle-mediated transport of HRP across the microvessel endothelium was observed.
- Complete recovery of normal BBB function, indicated by HRP exclusion, occurred within 15-30 minutes after MRI cessation.
Conclusions:
- Short-term clinical MRI procedures can transiently impair the blood-brain barrier in rats.
- The observed BBB alterations are temporary, with rapid recovery.
- Findings suggest a potential for temporary changes in central blood-brain permeability in human subjects undergoing MRI.