Magnetic resonance imaging (MRI) uses magnetic fields and radio waves to obtain images of organs and soft tissue such as muscle and fat. An MRI scanner is very advanced medical equipment that uses magnets, coils and computer images to create the scanned image of the body. The quality of the image depends on the interaction of all these parts.
MRI has less risk of side effects than other imaging tests because it does not use ionizing radiation. The use of MRI in the United States has grown very rapidly since its introduction in 1977. More than 7,000 facilities offer MRI and more than 26 million scans are performed each year.
A doctor may recommend an MRI scan to help diagnose many medical conditions – cancers, joint injuries, heart problems and spinal diseases, to name a few.
A high quality scan is important to make a correct diagnosis. Low quality MRI scans can lead to errors in diagnosis and treatment. Many factors can affect the quality of your MRI scan. This issue of HealthSmart! provides an overview of MRI technology and what you need to get a good scan.
Is MRI always necessary?
MRI is often the best test for many medical problems. It can detect diseases that an X-ray would not show. It is important to ask the doctor who ordered the scan if it is necessary and how the results will be useful for treatment. Work with your doctor to decide where the MRI will be taken.
Types of MRI scans
Traditional – Original MRI scanners are like passages with a closed end
Open Drill – Developed to help claustrophobic, elderly, obese and pediatric patients, this scanner offers greater patient comfort because it scans more openly. This scanner can leave the patient standing while scanning. Some types of examinations cannot be performed with an open MRI scan. Even with an open clamp unit, the patient’s face may be near the clamp ceiling.
Wide gauge magnets: A wide gauge scanner has a shorter passageway and is open at both ends. Scans can be performed with the patient’s head out of the opening if the brain is not scanned.
This scanner was developed for claustrophobic and obese patients and can perform all types of scans. It works with all types of patients, including children, and offers more space between the patient and the ceiling of the opening.
Factors for a high-quality MRI scan
Using a strong magnetic field and radio waves, MRI scans avoid the use of ionizing radiation such as that found in X-rays or CT scans.
If you and your doctor decide that an MRI scan is necessary, it is best to obtain images of the highest possible quality the first time for proper diagnosis and treatment. This is very important if you will make a decision about surgery based on the results. In addition, many insurance plans only pay for one scan.
In addition to the types of MRI scanners used, several factors contribute to the quality of the images.
Why does the MRI scanner make so much noise?
The typing and beating noises that you hear during an MRI scan are caused by the magnetic coils that turn on and off during the scan. These coils measure the signal coming from your body and use this information to create images. Since these noises are usually very loud, you will be given some kind of hearing protection.
During the MRI scan, you can choose between headphones with music or earplugs, depending on the type of scan being performed.
The latest MRI technology can be found in academic medical centres in large cities. Smaller communities may have fewer options. It is important to understand the types of scans offered by the chosen center.
The magnetic field or magnetic field strength helps determine the clarity of the images. Magnetic force is measured in units called Tesla (T), and scanners can have a force ranging from 0.5 T to 3.0 T. For some medical problems, a higher Tesla is required to produce high resolution images.
Higher resolution can produce better quality images. This helps the doctor reading the images to make better interpretations and diagnoses. Therefore, although an open MRI may be more comfortable for the patient, the resolution of the