Normal x-rays image calcium, so they are good to see bones. MRI scans image water, which makes them very useful because all tissues of the body contain various amounts of water. This allows high-resolution pictures of many organs and tissues to be taken that are invisible to standard x-rays. The MRI scan consists of a table that slides into a large cylinder.
Inside the cylinder is a magnet that, when operated, creates a powerful magnetic field. Soft tissue contains water molecules and the magnetic field acts upon microscopic substances called protons found in water.
A computer then organises these echoes into images. The MRI scan is used to investigate or diagnose conditions that affect soft tissue, such as:. The MRI scan provides clear and detailed images of soft tissue. That is why bone injury or disease is usually investigated with regular x-ray examinations rather than MRI scanning. You may be asked to wait while the radiographer checks the quality of the pictures.
In some cases, you may be asked to get back into the MRI scanner so that more pictures can be taken. If the pictures are satisfactory, you can get dressed and go home. There are no known long-term side effects from undergoing MRI. The MRI scan does not use ionising radiation to achieve its pictures. Be guided by your doctor but, generally, there are no special after-care instructions. A radiologist and other specialised doctors will examine and interpret the scan images.
You will need to make an appointment with your doctor to discuss the results. The MRI scan will help the doctor to plan appropriate treatment, if necessary. The MRI scanner is a complicated piece of equipment that is expensive to use and found only in specialised centres.
This allows for an expert review of your imaging by the applicably trained radiologist. Your images will be uploaded to a provincial picture archiving and communication system PACS — this technology provides electronic storage and convenient access to your medical images from multiple sources, such as your doctor, specialists, hospitals, and walk-in clinics. Your doctor will review your images and the report from the radiologist and discuss next steps with you, such as a treatment plan or the need for further diagnostic imaging or lab tests to ensure an accurate diagnosis.
Felson, S. Accessed May 3, Accessed May 2, Tretkoff, E. Skip to main content. Toll Free: You are here Treatment Diagnostic Tests. By Peter Ullrich, MD. Peer Reviewed.
In addition to pre-surgical planning, MRI scans are also very useful for the following: To rule out infection or tumor For patients who have had back surgery, to differentiate scar tissue from a recurrent disc herniation. It is specialized to produce the clearest picture of the area it is placed over. If the MRI scan will be used for surgical planning, the technologist may place small markers called fiducials on your forehead, face, or behind your ear.
Fiducials look like lifesavers and assist the surgeon during image-guided surgery. Do not remove or get the fiducials wet. When you are comfortably positioned, the table will slowly move into the magnetic field. The technologist will stay in constant contact with you. You can listen to music on a stereo system during your testing.
As the exam proceeds, you will hear a muffled "thumping" sound for several minutes at a time. This is the sound of the pictures being taken. There will be no pain or discomfort associated with the sound or exam. The exam usually takes 20 to 50 minutes. It is important that you relax and lie as still as possible. Any movement during this time will blur the picture. You may be given an injection of contrast dye gadolinium into your arm or through an IV to enhance the images. After the test is complete, the IV will be removed and you are free to go.
You may be told to drink lots of fluids to help your kidneys remove the contrast dye from your body. MRI is very safe. There are no known health risks associated with the magnetic field or the radio waves used by the machine. Some people are sensitive to the contrast agent and may develop an allergic reaction.
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