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Cerebral blood volume in a rat model of ischemia by MR imaging at 4.7 T
T A Kent1, M J Quast, B J Kaplan
1Department of Neurology, University of Texas Medical Branch, Galveston 77550.
Abstract:
Perturbation of the cerebral circulation by occlusion of the vertebral arteries and a carotid artery can be visualized by using MR imaging and the intravascular contrast agent Gd-DTPA complexed to albumin. This tracer consistently reduced the T1 relaxation time in the brain and blood. The difference between hemispheres was revealed by less T1 reduction in the occluded hemisphere and by an adjustment in the display contrast of images that revealed the territory of decreased perfusion. These results were confirmed by comparing them with cerebral blood flow using radioactive microspheres and the intravascular blood volume tracer 51Cr-EDTA. This method, combined with high-resolution MR imaging, can be applied to serial noninvasive studies of cerebral blood volume in ischemia and other conditions.
Insights
Magnetic resonance imaging (MRI) with a novel contrast agent visualizes cerebral blood flow changes. This technique accurately detects reduced blood volume in occluded brain hemispheres, aiding ischemia research.
Area of Science:
- Neuroimaging
- Cerebrovascular Medicine
- Medical Physics
Background:
- Cerebral circulation perturbations, such as arterial occlusion, significantly impact brain function.
- Accurate visualization of reduced cerebral blood volume is crucial for diagnosing and managing cerebrovascular diseases like ischemia.
Purpose of the Study:
- To evaluate the efficacy of MR imaging with an intravascular contrast agent (Gd-DTPA albumin) for visualizing perturbed cerebral circulation.
- To assess the ability of this method to detect and quantify differences in cerebral blood volume between hemispheres.
Main Methods:
- Cerebral circulation was perturbed by occluding vertebral and carotid arteries.
- MR imaging was performed using an intravascular contrast agent, Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) complexed to albumin.
- Results were validated against cerebral blood flow measurements using radioactive microspheres and 51Cr-EDTA.
Main Results:
- The Gd-DTPA albumin tracer effectively reduced T1 relaxation times in brain and blood.
- MR imaging revealed hemispheric differences, showing less T1 reduction in the occluded hemisphere.
- Adjusted display contrast enhanced visualization of territories with decreased perfusion, correlating with microsphere and 51Cr-EDTA data.
Conclusions:
- MR imaging with Gd-DTPA albumin provides a reliable method for visualizing cerebral blood volume changes.
- This noninvasive technique accurately detects reduced perfusion in occluded cerebral circulation.
- The method is suitable for serial studies in conditions like ischemia, offering valuable insights into cerebrovascular dynamics.