Magnetic Resonance Imaging (MRI) is a diagnostic procedure making use of magnetic waves and radio waves for detecting any abnormalities in the internal organs. The process involves visualizing internal organs of the human body using advanced medical technology in order to observe any unhealthy changes that may have taken place within.
Who performs MRI scan?
MRI scan is performed by a medical team comprising of a qualified radiologist and technicians well versed in the field of radiology.
Where is MRI scan performed?
MRI scans are performed at well equipped diagnostic centers or hospitals. The scanning room should be designed at par with international benchmarks. This ensures that the scanning procedure is perfect and provides error free results. Cost of MRI scan may differ according to city and facilities provided by diagnostic centers.
MRI machine is a hollow wide tube like structure with a sliding bed attached to it. Inside the tube, a magnetic field can be generated at the time of scan. A computer screen is part of the MRI machine. The computer screen displays the findings of MRI scan for the doctor to see. This type of MRI set up is known as closed MRI. The patient has to remain inside the hollow tube till the procedure is completed.
Open MRI is a variant of this set up. As the name suggests, the device is such that the patient is not confined to a closed environment. As opposed to a hollow tube, open MRI comprises of two magnetic plates placed parallel to each other. A sliding table is constructed such that it passes between these plates. A magnetic field is generated between the two plates at the time of scan. A computer screen displays all findings of the scan which are studied in order to confirm diagnosis.
Why is MRI Scan indicated?
MRI is usually the second line of investigation. It is uses advanced techniques to come to a conclusion about what could be affecting the patient. If primary investigations fail to provide satisfactory result, MRI is often advised in order to confirm the diagnosis. Some health conditions for which MRI is advised have been mentioned below:
- Cancerous and non-cancerous tumors
- Degeneration of inter-vertebral disc
- Spinal disorders
- Liver cysts
- Pancreatic cysts
- Intestinal disorders
- Gallbladder dysfunction
- Kidney cysts
- Urinary bladder dysfunction
- Muscular dysfunction
- Prostate gland dysfunction
- Thyroid gland dysfunction
Pre-requisites for undergoing MRI scan:
MRI scan is a rather long procedure and requires careful planning before it is performed. After assessing the patient’s health, medical history and previous investigation reports, the decision can be made whether MRI is needed. Prior to undergoing the MRI, following steps need to be followed:
- Patients are supposed to undergo a physical examination prior to the scan. This is done in order to establish that the patient does not have any gross health issues and is fit to undergo MRI.
- If any medication is being taken, patients have to inform their doctor about it. Dosage of some medications might be altered or stopped completely since a few days before MRI is done.
- Women who are undergoing MRI must inform the doctor if they are pregnant.
- Patients who have undergone pacemaker, stent, chemoport device implantationimplanted procedure in their body or patients who have undergone joint replacement surgery, should inform their doctor about the same.
- Patients are expected to arrive well in advance of the decided time for MRI. This is because, some preparations have to be done before undergoing the scan.
- Before the scan, patient is expected to leave all jewelery, accessories, metallic belongings outside the scanning room. They are even asked to change their clothes and dress into a sterilized hospital gown.
- Patients are asked to lie down on the sliding bed attached to the MRI machine. The position in which patients are asked to lie down depends on the part of body which is to be scanned.
Procedure of MRI scan:
The process of MRI scanning begins only after the radiologist ensures that the patient is prepped properly. The procedure which takes place is as follows:
- The table on which patient is lying slides into the hollow tube (open MRI) or between the two magnetic plates (closed MRI).
- A magnetic field of pre-determined intensity is generated within the MRI scanner. The magnetic field is focused on that part of the body which requiresis to be studied.
- The magnetic waves emitted, interact with the hydrogen atoms present within human body. This interaction results in the emission of radio waves from the hydrogen atoms.
- Magnetic waves and radio waves help to create a series of images of internal body organs.
- These images are displayed on computer screens in another room where the radiologist is monitoring the entire procedure.
- Diagnosis can be done on the spot and if the condition is serious, immediate medical measures can be taken to prevent the disorder.
- The procedure takes about 45 minutes to 90 minutes to get completed. The time period depends on patient’s health and probable diagnosis.
MRI scan is an outpatient procedure. This means the patient does not have to be admitted in the hospital before or after the procedure.
MRI with contrast:
This is a variant of normal MRI. The difference is that, a contrast heavy dye is injected into the patient’s veins prior to MRI scan. The dye spreads through patient’s blood stream to reach the target site.
It is said that using a contrast dye enhances the clarity of scan reports. However, pregnant women, little children, patients with kidney disorders, are not good candidates for contrast MRI. They have to undergo the scanning without contrast dye.
- After the MRI, patients are usually allowed to go home soon. However, some patients might feel giddy or nauseated from being into a closed space for a long time (closed MRI). In such cases the patients are kept under observation from some time and then discharged.
- Patients who have undergone contrast MRI, should take care for a couple of days after the scan, as the dye keeps getting excreted via urine.
- Such patients should take care to maintain toilet hygiene of the highest level. Their clothes and utensils should be washed carefully.
- Pregnant women who undergo MRI scan as advised to visit their gynecologist for a check up after the scan.
- Children who undergo MRI scan should be monitored carefully after the scan.
Advantages and Disadvantages of MRI scan:
- It is a very precise method of investigation and provides error free results most of the times.
- It is a non invasive method and does not require any surgical procedure to be performed on the patient.
- It does not require exposure to X-Rrays or other harmful radiation as opposed to C.T. Scan and X-Ray.
- Closed MRI scanner is a hollow tube which tends to impart a feeling of claustrophobia in some patients.
- Patients who need to undergo contrast MRI may suffer from side effects due to the dye. Nausea, vomiting, cramps are some of the common side effects of contrast dye.
- Contrast MRI has a lot of post-procedure restrictions to be followed. They have been described above.
Strength of Magnetic Field during MRI scan:
The strength of magnetic field used during MRI scan is determined depending on many factors like the patient’s age, general health status, probable diagnosis. In case of females, whether the woman is pregnant, presence of any allied health disorder etc.
Greater the strength, higher is the clarity of MRI scan.
However, higher strength of magnetic field also comes with some disadvantages. Therefore higher strength of magnetic field is not always used in every MRI scan.
General uses of MRI:
The health conditions which can be diagnosed by performing MRI have been mentioned earlier in this article. MRI can be utilized in the following situations:
- Primary investigation: MRI can be used to detect a hoard of disorders affecting various parts of the body.
- Follow up investigation: MRI can be performed for patients as a repeat investigation when it has been already performed before. Successive reports of MRI are helpful in comparing the changes which have taken place in internal body tissues after commencement of treatment for that particular disorder.
- As a guide: MRI scan is used as a guide for performing biopsy procedures. This helps the pathologist to visualize internal tissues while performing the biopsy and guides him/her to the correct site where biopsy is to be performed. It also helps in avoiding injury to other healthy tissue from the tools used for biopsy.
MRI is a very advanced diagnostic technique and helps in detecting various types of disorders. Patients should remember to follow all instructions given to them prior to and after the procedure.
MRI should not be performed without a doctor’s prescription. It may not suit everyone. Patients about to undergo MRI, should obtain all possible information about do’s and dont’s and related to the procedure of MRI. This makes it very convenient for them to undergo the procedure as they know details about it.