The Knowledge Zone
WHAT DOES THE EQUIPMENT LOOK LIKE?
MRI imaging requires a very strong and accurately uniform magnetic field. In order to create a strong and uniform magnetic field, the best engineering design is a cylindrical shape called a solenoid. As such all high quality MRI units utilizes this cylinder-shaped design with patient on a sliding bed at the centre. In the most modern systems, the opening of the cylinder is made larger (70 cm) than the original designs (60 cm). This is called the wide bore design and is more comfortable for the patient.
Our new MRI unit in Port-of-Spain utilizes this wide bore design.
Other MRI machines are open on the sides (open MRI) but since these systems do not use the solenoid design they have a weaker magnet and are not as uniform as the cylindrical systems. This does diminish the quality of the MRI images and lengthens the time to take the images. As such certain types of MRI exams cannot be performed using open MRI.
HOW DOES THE PROCEDURE WORK?
Unlike conventional x-ray examinations and computed tomography (CT) scans, MRI does not utilize ionizing radiation. Instead, radio signals and magnetic fields re-align the billions of hydrogen atoms that naturally exist within the body. This does not cause any chemical changes in the tissues. As the hydrogen atoms return to their usual alignment, they emit different detectable radio signal which can be captured by a device placed close to the body part being imaged. The MR scanner captures these signals and powerful computers process the information to create a 3D picture of the tissues scanned.
Different MRI techniques can make fluid bright and tissues dark or vice versa or can look for blood flow or other characteristics of the tissue which will help our radiologist and your doctor make the best diagnosis of your condition. MRI scanning is the most flexible and sophisticated imaging technique available in modern medicine. The images can also be studied from different angles by the interpreting radiologist. The differentiation of abnormal (diseased) tissue from normal tissues is usually better with MRI than with other imaging modalities such as x-ray, CT and ultrasound. It also provides exquisite anatomical detail for planning treatment once the diagnosis is made.
WHAT WILL I EXPERIENCE DURING AND AFTER THE PROCEDURE?
MRI exams are painless and most patients tolerate it very well and feel very relaxed during the process. However, some patients can experience a sense of being closed-in (claustrophobia) while in the MRI scanner. Sedation can be arranged for those patients who anticipate anxiety, but fewer than one in 20 actually requires medication and our caring staff are very experienced and trained in making the scan process very comfortable.
It is normal for the area of your body being imaged to feel slightly warm, but if it bothers you, notify the technologist. It is important that you remain perfectly still while the images are being obtained, which is typically only a few seconds to a few minutes at a time. You will know when images are being recorded because you will hear loud knocking sounds from the scanner. You will have the option of listening to soothing music with headphones or wear ear plugs to reduce the intensity of the sounds made by the MRI machine. You will be able to relax between imaging sequences, but will be asked to maintain your position without movement as much as possible.
The technologist will be able to see, hear and speak with you at all times using a two-way intercom. MRI scanners are air-conditioned and well-lit.
In some cases, intravenous injection of contrast material may be administered before certain images are obtained. The small intravenous needle will cause a brief pinch when it is inserted and there is also a very small chance of irritation of your skin at the site of the IV tube insertion. Some patients may sense a temporary metallic taste in their mouth after the contrast injection.
If you do not require sedation, no recovery period is necessary. You may resume your usual activities and normal diet immediately after the exam. On very rare occasions, a few patients experience side effects from the contrast material, including nausea, headache and pain at the site of injection. Similarly, patients are very rarely allergic to the contrast material and experience hives, itchy eyes or other reactions. If you experience allergic symptoms, notify the technologist immediately so that he may initiate treatment prescribed by our radiologist. If you do require sedation, you will be required to be monitored for a period of time after the scan before you are able to leave the centre with someone else driving you home.
WHO INTERPRETS THE RESULTS AND HOW DO I GET THEM?
A radiologist, a doctor specifically trained to supervise and interpret radiology examinations, will analyze the images and will create a signed report which we will forward to your primary care or referring physician, who will share the results with you.
Follow-up examinations may be necessary. Your doctor will explain the exact reason why another exam is requested. Sometimes a follow-up exam is done because your doctor needs more information with additional views or a special imaging technique. A follow-up examination may also be necessary so that any changes can be monitored over time. Follow-up examinations are sometimes the best way to see if treatment is working or if the condition is stable or changed over time.