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Middle cerebral artery occlusion in rats studied by magnetic resonance imaging
R H Bradley1, T A Kent, H M Eisenberg
1Division of Neurosurgery, University of Texas Medical Branch, Galveston 77550.
Abstract:
Ischemia due to middle cerebral artery occlusion was studied in 29 rats from 1 to 24 hours after occlusion using magnetic resonance imaging. Images were made before and after the injection of a superparamagnetic iron oxide compound, AMI-25. Subtraction images demonstrated the region of perfusion deficit as early as 1 hour after occlusion, earlier than conventional T2-weighted images. The area of altered perfusion detected by this technique (subtraction imaging after AMI-25 administration) correlated with that demonstrated by iodoantipyrine autoradiography. Since this magnetic resonance technique can be used to serially estimate the location and size of the ischemic area, the technique can be an important adjunct to metabolic studies of focal ischemia using magnetic resonance spectroscopy. The technique may have clinical applications as well.
Insights
Magnetic resonance imaging with AMI-25 detects perfusion deficits in middle cerebral artery occlusion rats earlier than T2-weighted images. This technique aids in studying focal ischemia and may have clinical applications.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Focal cerebral ischemia, such as from middle cerebral artery occlusion, is a critical condition requiring accurate and timely diagnosis.
- Conventional imaging techniques may not always provide the earliest detection of perfusion deficits.
Purpose of the Study:
- To evaluate the efficacy of magnetic resonance imaging (MRI) with a superparamagnetic iron oxide contrast agent (AMI-25) for early detection of perfusion deficits in a rat model of middle cerebral artery occlusion.
- To compare the sensitivity of this MRI technique with conventional T2-weighted imaging and autoradiography.
Main Methods:
- Twenty-nine rats underwent middle cerebral artery occlusion.
- Magnetic resonance imaging was performed before and after injection of AMI-25.
- Subtraction imaging was used to identify perfusion deficits.
- Results were compared with conventional T2-weighted images and iodoantipyrine autoradiography.
Main Results:
- Subtraction imaging after AMI-25 administration detected perfusion deficits as early as 1 hour post-occlusion.
- This detection occurred earlier than with conventional T2-weighted images.
- The area of altered perfusion identified by MRI correlated well with iodoantipyrine autoradiography findings.
Conclusions:
- MRI with AMI-25 and subtraction imaging is a sensitive method for early detection of perfusion deficits in focal cerebral ischemia.
- This technique allows for serial estimation of the ischemic area size and location.
- The method shows potential as an adjunct to magnetic resonance spectroscopy studies and may have clinical utility.