About Brain Perfusion and Brain Diffusion
A brain perfusion scan is an imaging technique that is of great use when a stroke has occurred.
Brain perfusion can be performed using either a CT scan or an MRI scan. Recent technological advances in these scanners have made it easy to image the brain in detail never before possible. By quickly detecting a stroke and identifying its cause, doctors can more rapidly take action to limit, and potentially reverse, its damaging effects.
With brain perfusion, images are quickly taken over a 60-75 second time frame to watch the circulation in the brain.
Contrast medium is rapidly injected during the scan. It is the circulation of the contrast that is captured in the images. With CT perfusion, multi-slice CT scanners provide the speed needed to determine the extent of brain tissue that has been deprived of its blood supply during the first few hours after the onset of a stroke. With MR perfusion, an ultra-fast technique called echo-planar imaging, or EPI, is used to generate the images of the brain tissue and blood supply. With both techniques, a radiologist can quickly evaluate any areas where the blood supply has been disrupted or decreased due to the narrowing or blockage of arteries.
A brain diffusion scan is performed in an MRI scanner and also uses EPI.
MR Brain diffusion utilizes the principle of microscopic water movement in the brain tissue. Under normal conditions, water in the brain tissue moves rather freely. When a disruption to the blood supply of the brain occurs, the tissue will swell. This swelling will decrease the freedom with which the water can move about. The restriction in movement is visible on the MR diffusion scan images.
MR brain diffusion done along with MR brain perfusion yields information about the amount of brain tissue that has suffered irreversible damage and also the amount of tissue that is “at risk” of irreversible damage, but may still be salvageable.
Brain perfusion and diffusion are often combined with cerebral angiography to provide a comprehensive picture of the circulatory activity in the brain. With this comprehensive picture, a radiologist can see not only the area of the brain affected by the blood flow disruption, but also in many cases, the cause of the disruption itself. A team of physicians can then determine the best course of treatment to minimize the effects of stroke.
Brain perfusion and brain diffusion are emergency exams that are performed by RIA radiologists at the following RIA partner hospitals:
- Medical Center of Aurora
- Littleton Adventist Hospital
- Porter Adventist Hospital
- Sky Ridge Medical Center
- Swedish Medical Center