MRI of the Brain
When there is sudden vision loss, the brain may be imaged. There are a number of different pathologies (causes) that they will be using imaging to rule out, but common ones include brain tumors, strokes, and multiple sclerosis. While a CT and MRI have similarities, each have advantages to be able to view different disease states. Depending on your underlying diseases and presentation, they may order one or both of these.
A MRI of the brain uses a magnetic field and radio waves to get multiple views of the brain to get a 3D image of your brain. During a MRI, your body will be on a table that may move back and forth in the MRI machine which contains the magnets. A MRI can be done with or without IV contrast dye. This contrast dye is gadolinium which helps to visual blood vessels better; however, the decision if you receive contrast dye or not will depend on a few factors but primarily what structures they need to see. Since a MRI is a smaller space and is tubular, it is important to note if you are claustrophobic or not. If you are, they may give you a relaxing medication to help ease your anxiety during the exam.
To prepare for a MRI of the brain, they will have you change into a hospital gown and remove all metal objects including piercings and jewelry. You will complete a screening tool to ensure that the MRI is safe for you and there are no contraindications. If you are receiving IV contrast, they will place a peripheral (arm) IV in order to give you the contrast. You will lie on a table which will be moved into a tubular machine, which is the MRI machine. Since the sounds of the machine is loud, they may give you ear plugs or headphones to listen to music. After you are positioned correctly in the machine, the technicians in the room will move behind a window to where the scanner controls are, but they will be able to speak to you via speakers. Once the exam begins, you will lie still for the duration of the exam and the table may move back and forth a little to get images of different parts of the brain. Throughout the exam, there will be loud banging sounds which are normal. If they use IV contrast dye, they will either inject it at the beginning of the MRI scan or midway through the exam after they have images without contrast. When it is injected, you may feel a sensation of flushing, nausea, or a salty taste in your mouth. This will only be brief and will reside quickly. Typically, a MRI of the brain takes about 45 - 60 minutes with most of this being the prep time and the actual exam lasting around 30 - 45 minutes. Once the MRI scan is complete, you will be removed from the machine and if you have an IV line, this will be removed.
