Magnetic Resonance Imaging (MRI)

Posted By: admin | Posted on: 15 November, 2016 04:54 am

MRI scan Machine
MRI Scan Machine

(Image Credits: shutterstock.com)

 

What is a MRI Scan?

Magnetic Resonance imaging (MRI) scan utilizes strong magnetic fields and radio frequency waves to generate detail image inside  your body.

It does not involve the use of radioactive material or x-rays so the technique is ideal for screening and determining very early stages of certain diseases such as cancer, stroke, and Alzheimer’s disease. It is also very useful for diagnosis of injuries, disorder of the brain, spine, breasts, bones and other tissue and organs of the body.

How is MRI scan test different from PET or CT scan?

MRI, PET, and CT scan tests are all diagnostic imaging technique use to detect diseases in the body, but they work differently. MRI utilize magnetic field and radio waves which line-up with particle of the cells of the body to produce detailed images of the structures and organs.

On the other hand, PET (Positron Emission Tomography) scan involve injection of the person undergoing the test with a radiotracer that has very small radioactive sugar component as the cell uptake and metabolize the tracer. Radioactive energy is emit which is detect and used to generate image on a 3D computer. Thus PET scan reveals whether the tissues or organs of the body are functioning properly or not.

CT scan uses small doses of ionizing radiation called x-rays to obtain images inside of your body as the scanner rotates and reveals any abnormality in the organ or tissue structures.

Which body parts  is commonly scan by MRI?

  • Brain and spinal cord
  • Throat
  • Heart and blood vessels
  • Lungs
  • Breasts
  • Liver
  • Pancreas
  • Uterus and cervix
  • Bladder
  • Prostate
  • Abdomen
  • Colon
  • Bones and joints

Why is it important to have an MRI scan?

MRI scan can be use to detect disease states in almost all of the organs and tissues of the body. Because of the safeness of the technique, it is very useful for screening delicate organs like the breast, prostate, and the spine, as well as, the non-delicate organ of the body as shown  below:

Brain: It can be used to detect aneurysms hemorrhage, area affect by stroke, cancer and blood vessels abnormality called atrioventricular malformations (AVM).

Spinal cord: To check spine injury, disc problem, and development of spinal cancer.

Throat: To diagnose or confirm a spread of cancer in the neck.

Heart and blood vessels: To evaluate heart diseases such as obstruction of blood flow to the heart muscle, the function of the valves, damage caused by heart attack or stroke.

Lungs: To assess abnormal masses such as cancer and determine if it has spread.

Breasts: To screen for high risk breast cancer individual.

Liver: To screen for cancer, determine the spread of cancer and recurrence.

Pancreas: To evaluate diseases such as cancers, infection and stones of the pancreas.

Uterus and cervix: To look for abnormal growths such as fibroid, polyp and cancer and to determine the best treatment option.

Bladder: To look for bladder cancer, what stage it is at and bladder infection.

Prostate gland:  To evaluate the stage of prostate cancer, to check if it has spread and to determine if the gland has an infection.

Abdomen: To check the abdomen and the pelvic area for tumors .

Colon: To determine bowel perianal disease  as well as, colon cancer and to check if it has spread to other body part.

Bones and joints: To look for injuries, torn cartilage and ligaments, soft tissue cancer and bone infections.

What is the procedure for MRI scan?

MRI technique makes use the fact that the human body consist largely of water (75%), which is present in the cells, joints, and flowing fluids. Water molecules have weak positive (proton) and negative (electron) charges. The weak protons are sensitive to the magnetic field.

During MRI, the scanner magnetic field aligns with the protons of the cells of the organs or tissues. Subsequently, the radio frequency waves are turned on, which knock out the protons from alignment. When the radio waves are turned off again, the protons go back to realign with the magnetic field, which in turn emit radio signal, detected by radio detectors to create cross-section images of organ and tissues of your body, using 3D computer software.

MRI serve an important diagnostic tool, as it makes use of the fact that the proton signal produced by healthy cell are different from those produced by abnormal tissues, thus any aberrance in tissue, organs bones and joints can be assessed.

How do I prepare for the MRI scan test?

The Day your doctor ordered the MRI test

  • Remind your doctor about any illness you might have and all the medications you are taking, including over-the-counter drugs.
  • If you have kidney disease, MRI contrast can cause more damage to the kidneys so remind your doctor about any kidney illness, in case an alternative test will be s.
  • Remind your doctor about any metal device you are wearing so he/she can plan for an alternative test.
  • Ask your doctor if contrast will be needed for your MRI scan, since this will require you to fast for 4 hours prior to your scan test.
  • Let your doctor know if you are pregnant to allow her to decide whether the MRI scan will be alright for a fetus.
  • Let your doctor know if you are claustrophobic, that is, afraid of closed spaces, so she can arrange for you to have a medication to make you feel sleepy and calm on the day of your scan.

The Day before the MRI test

You will either get a letter in the mail or receive a phone call from a staff of the facility where you scheduled your appointment, telling you how to prepare.

The staff might tell you the following:

  • Eat and drink normally if contrast will not be required. But if contrast was ordered along with your MRI scan, you must NOT eat 4 hours before your scan time. This means that if you are having contrast MRI scan in the morning, you cannot have breakfast. If it is at 4:00 PM, your last meal before the scan should be at mid-day.
  • Take your medications like you’ve always had.
  • Avoid wearing jewelry, watches, wigs, hairpin, denture, hearing aid, underwire bra eyeglasses to the scanning room, as anything that has a metal component will either make the magnetic field so powerful that it could to cause harm to you, ruin the scanner or both.
  • Put on easy-to-wear outfits as you will be asked to change into a hospital gown when you get to the facility.
  • Arrive at the facility 30 minutes before the schedule time to do paperwork, including filling out MRI screening form.

You must tell the staff the following:

  • Any medication you are taking.
  • The need to take medication for your claustrophobia, so the relevant preparation will be made. Let him/her know if somebody will accompany you to drive you back home.
  • Tell the staff if you have kidney disease, as the use of contrast can make it worse.

The Day of the MRI test

  • MRI scanning without contrast does not require you to fast before the procedure, so you can eat regularly. However, if you are told the test will be perform with contrast, you have to fast 4 hours prior to the schedule time.
  • Take your medications like any regular day, unless special instructions are given to you.
  • You will wait in the waiting area for the Radiology Technologist to come and escort you.
  • You will be ask to change into a hospital gown and remove any jewelry, including a watch, necklace, and earrings.  Remove hairpins you might have in your hair.
  • You will be led to the scanning area. If a contrast is require, it will be administer to you, either by mouth or you will have intravenous (IV) injection in your arm vein. The contrast will make your MRI images clear and show better detail.
  • The Radiology Technologist will ask you to lie flat on your back on the scanner bed
  • You will be slid into the tunnel-shape scanner, like what you see below:
MRI Scanning Machine-patient lie flat on the scanner bed
MRI Scanning Mahine

 

  • The Technologist will operate the scanner and monitor the detection of signals from another room but you can communicate through the scanner microphone.
  • The MRI scanning will take 30-60 minutes. You should remain still as the scanning is being perform because movement will make the resulting image appear blurry.
  • This is then channel into 3D computer software which creates images of the scan.
  • The scanner will detect metabolic change that are taking place in the brain when you are performing the task.
  • During the MRI procedure, the scanner might be noisy, so you may be provide with ear plugs or headphone to minimize the effect.

After your MRI scan

  • You are free to resume regular activities, once the Radiography Technologist say you can leave.
  • If you are medication for your claustrophobia, you will not be able to drive . The ideal situation will be to bring somebody to drive you back home; otherwise, you will have to wait for a while until you are no longer drowsy before you can drive again.

What are the side effects of MRI scan?

  • MRI scan is very safe, as there are no radioactive materials or x-rays involve.
  • If a contrast dye is given, it does not contain iodine that might cause an allergic.If the contrast injection is administer intravenously (IV), there will be a little pain from the prick of a needle and skin redness which will not last long.If you have any implant device, you should remind your doctor and also inform the Radiology Technologist, as the magnetic resonance can prevent the device from working.

What are the risks of MRI scan?

Although the strong magnetic field is used in MRI imaging, any metal around your body or within your body will pose a safety hazard. It has been report by MRI maintenance Engineers that in the presence of metal object, the strength of MRI magnet become so strong that it can trap, injured, or even kill an individual having the scan test. In addition, if the magnetic field comes into contact with metals, it will interfere with the scanning and the subsequent generation of images.

Remind your doctor on the day your MRI scan was order and also tell the Radiology Technologist if you have any of these metal devices:

  • Heart pacemaker
  • Heart mechanical replacement valves
  • Implantable cardio-converter defibrillator (ICD)
  • Metal-on-metal hip implants
  • Inner ear (cochlear) implants
  • Hair metal clips
  • Have had a bullet or shrapnel injury
  • If the use of a contrast material is require, it is unlikely for it to cause allergic reactions.
  • If you are pregnant, tell your doctor, as the procedure might harm the fetus. This has not been prove but it is important safety precaution.

What are the limitations of MRI scan?

  • MRI scan has shown to sometime give significant false positive so another test can  be need to confirm an abnormality.
  • It is more expensive than a mammogram and so not everybody can afford it.
  • The MRI scan take a long time so individual that are nervous about close space (claustrophobia) might need medication to calm them down.
  • It is difficult to scan certain body areas like the rectum.
  • Individuals who wear metal devices may not be able to have MRI test for diagnosis because of the danger it might pose.
  • Children might have to be Anesthetisa to stay still since the scan take a longer time.
  • Some tattoos dark inks might contain pieces of metals that will interfere with the quality of the imaging.

How does the Radiologist distinguish between Healthy and diseased organ from the MRI scans?

We all marvel at how the Radiologist is able to tell the difference between a healthy and a diseased structure or organ from the scan. It is good to know that they are highly train and they also work as a team to interpret difficult result. If they are uncertain about the scanning results, they will ask you to return and obtain more precise images, or recommend another test to confirm what they have doubts about.

You may look at a few MRI scanned images below which tell dramatic differences between healthy organ or organ slices and disease states:

Image 1A shows MRI scan of liver metastasis cancer, pointed with the white arrow. The cancer is treat by ablation  in using heat generating high-frequency electrical current.

Contrast MRI of Liver Metastasis cancer
Contrast MRI of Liver Cancer

Image 2 shows the use of 3D MRI in detecting early stage of left breast cancer (L1) and how the cancer developed to maturity (L2) over a time. The right breast are affect and  remain healthy.

Breast MRI of early stage cancer and developed cancer
MRI of Breast With Cancer

 

Reference: https://www.medscape.org/viewarticle/830849_9

 Image 3 shows how MRI scan are use to detect an early stage of prostate cancer. Early detection means that the affected individual has a chance of getting treatment that would completely bring about cure.

MRI of Prostate showing healthy and early stage of prostate cancer
MRI Showing Prostate Cancer

Reference :https://www.alta-klinik.com/prostate-cancer.html

How much does it cost to have an MRI scan?

In as much as imaging tests provide very good means for identification of several diseases, they can be quite expensive so you need to shop around. Pricing varies from facility to facility and from state to state. Not all insurance companies cover out-of-network expenses so you need to check with your health insurance provider before you check-in for your scan test.

Pricing also varies from location to location and from facility to facility. If you took a look at the Table provided below, you will find out that certain individuals have paid too much for their MRI scans. Go to cheapimaging.com and check prices in your area.

You can also visit saveonmedical.com or newchoicehealth.com, plug in the type of scan you want to have and your location so you can choose a facility that you can afford for your scan. A lot of facilities will give you discounts if you pay your bill by cash. Put these information into consideration for the best deal.

Please review these links for more information:

What are the risks of the Scan ?

For MRI Scan treatment costs in India  – Please refer to the following link click here

References:

  1. Kuhl CK, Schrading S, Bieling HB, et al. MRI for diagnosis of pure ductal carcinoma in situ: a prospective observational study. The Lancet. 2007; 370:485–492.
  2. Hagen AI, Kvistad KA, Maehle L. Sensitivity of MRI versus conventional screening in the diagnosis of BRCA-associated breast cancer in a national prospective series. The Breast. 2007; 16: 367–374.
  3. https://mrimetaldetector.com/blog/2009/03/mri-and-metal/
  4. https://www.researchgate.net/figure/24355019_fig4_Fig-4-MRI-before-and-after- radiofrequency-ablation-of-liver-metastasis-T2-weighted
  5. https://www.medscape.org/viewarticle/830849_9
  6. https://www.alta-klinik.com/prostate-cancer.html
  7. https://cheapimaging.com/
  8. https://www.saveonmedical.com
  9. https://www.newchoicehealth.com/places/oklahoma/ Oklahoma-city/mri
  10. https://www.comparemricost.com/