From CVA to CT
The May/June 2012 CT Edition of the Journal of the American Society of Radiologic Technologists has an excellent article about stroke and CT perfusion. The information outlined is invaluable to any technologist who has to perform perfusion scans. When they started doing them at my former hospital I received very little training on how to do the scan and the post processing. At first I was only told the bare bones of what to do and never told why I was doing it. This "why" component is a necessity for me to understand and learn something properly.
When a patient came in with stroke symptoms it was just as urgent as a trauma. Trying to hurry and do a scan I wasn't completely comfortable with made it even more difficult. I eventually had to seek out staff to educate me on the entire protocol. The post processing is time consuming and requires detailed focus. Again, an understanding of "why" is essential to performing this task correctly. The article discusses how to select a reference artery and vein, which is the first step in the post processing.
The stroke and CT perfusion article discusses the entire process. It has excellent images to demonstrate what the gray scale of the MIPs (maximum intensity projections) should look like. It also shows the color coded perfusion map demonstrating the MTT (mean transit time) or time to drain. It shows the areas that drain the slowest to be in red, yellow, green and finally blue. Blue represents the area in the brain that drains the fastest. Areas that are red indicate infarction while yellow highlights penumbra.
CT perfusion is an effective method for diagnosing acute ischemic stroke. If you do these scans at your hospital make sure you understand each step of the scan and the post processing. Talk to your radiologists and have them discuss with you what they are looking for and how you can improve your work.
This extensive scan may be time consuming but remember you are providing images that can prove to be life saving.