Related Experiment Video
Updated: Apr 12, 2026
Monitoring Blood-Brain Barrier Opening in Rats with a Preclinical Focused Ultrasound System
Published on: September 13, 2024
MRI measurement of blood-brain barrier transport with a rapid acquisition refocused echo (RARE) method
Jeffrey H Walton1, Kit Fai Ng2, Steven E Anderson3
1NMR Facility and Biomedical Engineering Graduate Group, University of California, Davis, USA.
Abstract:
Dynamic Contrast Enhanced (DCE) MRI is increasingly being used to assess changes in capillary permeability. Most quantitative techniques used to measure capillary permeability are based on the Fick equation that requires measurement of signal reflecting both plasma and tissue concentrations of the solute being tested. To date, most Magnetic Resonance Imaging (MRI) methods for acquiring appropriate data quickly rely on gradient recalled echo (GRE) type acquisitions, which work well in clinical low field settings. However, acquiring this type of data on high field small animal preclinical MRIs is problematic due to geometrical distortions from susceptibility mismatch. This problem can be exacerbated when using small animal models to measure blood brain barrier (BBB) permeability, where precise sampling from the superior sagittal sinus (SSS) is commonly used to determine the plasma concentration of the contrast agent. Here we present results demonstrating that a standard saturation recovery rapid acquisition refocused echo (RARE) method is capable of acquiring T1 maps with good spatial and temporal resolution for Patlak analysis (Patlak, 1983) to assess changes in BBB Gd-DTPA permeability following middle cerebral artery occlusion with reperfusion in the rat. This method limits known problems with magnetic susceptibility mismatch and may thus allow greater accuracy in BBB permeability measurement in small animals.
Insights
This study presents a new Magnetic Resonance Imaging (MRI) method for accurately measuring blood brain barrier (BBB) permeability in small animals. The technique overcomes issues with geometrical distortions, improving precision in permeability assessments.
Area of Science:
- Biomedical Imaging
- Neuroscience
- Pharmacokinetics
Background:
- Dynamic Contrast Enhanced (DCE) MRI is vital for assessing capillary permeability.
- Quantitative permeability measurements often rely on the Fick equation, needing plasma and tissue solute concentrations.
- Gradient recalled echo (GRE) MRI methods face geometrical distortions in high-field small animal preclinical imaging, particularly for blood-brain barrier (BBB) studies.
Purpose of the Study:
- To introduce a novel MRI method for accurate BBB permeability assessment in preclinical small animal models.
- To address limitations of existing MRI techniques, specifically geometrical distortions caused by susceptibility mismatches.
- To enable precise measurement of contrast agent (Gd-DTPA) permeability across the BBB.
Main Methods:
- Utilized a standard saturation recovery rapid acquisition refocused echo (RARE) MRI sequence.
- Acquired T1 maps with high spatial and temporal resolution suitable for Patlak analysis.
- Applied the method to assess BBB Gd-DTPA permeability changes in a rat model of middle cerebral artery occlusion with reperfusion.
Main Results:
- The RARE method successfully acquired T1 maps with adequate resolution for quantitative permeability analysis.
- Demonstrated the capability of the method to measure changes in BBB permeability post-stroke.
- The RARE technique effectively mitigated geometrical distortions associated with susceptibility mismatches.
Conclusions:
- A saturation recovery RARE MRI method provides accurate T1 mapping for BBB permeability studies in small animals.
- This approach overcomes limitations of GRE sequences, offering improved accuracy in preclinical BBB research.
- The presented method enhances the reliability of measuring BBB permeability changes in disease models.
