Modalities

 

MRI & MRA | CT Scans | PET Fusion CT Scans | Mammograms

 

Magnetic Resonance Imaging (MRI) Scan:

 

What is a Magnetic Resonance Imaging (MRI) Scan?

 

An MRI scan uses a powerful magnet to take pictures of the inside of your body. This is an excellent test because it allows your doctor to see your body in narrow slices, each about one quarter of an inch thick. For example, imagine that you are slicing a loaf of bread and taking a picture of each slice. It can view slices from the bottom (axial) front (coronal), or sides (sagittal), depending on what your doctor needs to see.

 

MRI can also be used to view veins and arteries, called Magnetic Resonance Angiography (MRA). Standard MRI can’t see fluid that is moving, such as blood in an artery, and this creates “flow voids” that appear as black holes on the image. The MRA uses a contrast dye (gadolinium) injected into the patient’s vein to help the computer “see” the arteries and veins. The contrast is also used to view tumors and Arteriovenous Malformations (AVM’s).

 

How does it work?

 

The scan works by using a magnet, radio waves, and a computer to create detailed images. Your body is made up of hydrogen atoms (the human body is 80% water), which are magnetic. When your body is placed in the magnetic field, these atoms line up with the field, much like a compass points to the North Pole. A radio wave “knocks down” the atoms and disrupts their polarity. The time it takes for the atoms to return to their original alignment is picked up by the sensor. This information in essence measures the water content (or fluid characteristics) of different tissues and is processed by the computer to create a black and white image. The image is highly detailed and can show even the smallest abnormality.

 

What does an MRI show?

 

MRI gives very detailed pictures of the brain and spine. Air and hard bone do not give an MRI signal so these areas appear black. Bone marrow, spinal fluid, blood and soft tissues like brain vary in intensity from black to white, depending on the amount of fat and water present in each tissue and the machine settings used for the scan. The radiologist compares the size and distributions of these bright and dark ares to determine whether a tissue is healthy.

 

Nearly every part of the body may be studied with MRI. Organs within the chest and abdomen, such as the heart, liver, bladder and kidneys can easily be seen. MRI is also very sensitive to changes in cartilage and bone structure resulting from injury, disease or aging. Clear pictures often provide information not available through other medical testing and may actually eliminate the need for exploratory surgery.

 

Compared to the standard MRI, we offer the latest in technology, the Short Bore MRI. This machine is similar to the standard, but is about half the length. If you are having pictures taken of your head, then your legs will be clear from the tube. If your back is being images, then your head will be outside the machine. You may find this option more tolerable if tight spaces make you uncomfortable.

 

Our center offers sedation for Patients with discomfort in the MRI. With consent from your treating physician, and a driver to assist your ability to leave our center, we may offer this before you are scanned. Our staff will ensure that this sedation is safe for you based on current medical history.

 

Who performs the test?

 

A radiology technologist will perform the test in the MRI suite of the Radiology department of our outpatient imaging center. The radiologist will review the images and report their findings.

 

How should I prepare for the test?

 

You should avoid caffeinated beverages. Wear loose clothing and remove all objects that would get in the way of the scan, such as hairpins, jewelry, etc. You may need to change into a gown provided in our center, depending on what part of your body is being imaged.

 

What happens during the test?

 

You will lie on a movable bed with your head cradled on a headrest and your arms at your sides. An antenna device called a “coil” will be placed over and under the area being scanned. It is specialized to produce the clearest picture of the area in which it is placed. When you are comfortably positioned, the table will 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 and injection of gadolinium, which is a contrast agent used to enhance the image.

 

What are the risks?

 

MRI is very safe. There are no known health risks associated with the magnetic field or the radio waves used by the machine. Sometimes a substance called a contrast agent is injected into your body to enhance the image. All contrast agents are FDA approved and safe, though some people are especially sensitive to it.

Some special circumstances limit the use of a magnetic field, so it is important for you to tell our staff if any of the following apply to you:

 

  • cardiac pacemaker or artificial heart valve.
  • metal plate, pin or other metallic implant.
  • interurine device, such as copper-7 IUD.
  • insulin pump or other infusion pump.
  • aneurysm clips.
  • previous gunshot wound.
  • inner ear implant.
  • been a metal worker (exposed to metal in eyes).
  • permanent (tattoo) make-up.

 

Any metallic substance on your body can affect the quality of the images. It can also cause discomfort or injury to you while placed in magnetic field, and may exclude you from the exm.

 

Also, be sure to tell the staff if you’re pregnant. The American College of Radiology recommends that MRI scanning not be done in the first trimester of pregnancy. After the first trimester, there is no definitive research indicating that MRI is contraindicated in pregnancy. However, you will need to obtain a written order from your gynecologist for the test to be performed.

 

How do I get results?

 

The radiologist will promptly review your images and communicate directly with your referring doctor, who in turn will discuss the results with you. The estimated turn-around time for reports to be distributed to your physician, is 24 hours. This is typical timing unless your doctor has requested a Stat exam, in which the Radiologist will rush your dictation to the treating physician.