If your doctor suspects you suffer from deep vein thrombosis (DVT), he will need to perform a series of tests to accurately make a DVT diagnosis. One test he may need to perform is a magnetic resonance imaging (MRI) scan.

While a DVT diagnosis can be difficult to make, MRI scans offer doctors a non-invasive method of accurately diagnosing DVT, especially when the blood clots are located in the pelvis and/or thighs.

What is Deep Vein Thrombosis?

Deep vein thrombosis is a condition that results when blood clots form in the deep veins, often those found in the leg muscles. While many blood clots will dissolve on their own, DVT can lead to pulmonary embolism, a life-threatening condition that occurs when DVT clots bread loose and travel to the lungs. If these blood clots restrict blood flow to both the lungs and the heart, results can be fatal. As a result, pulmonary embolism is a medical emergency that requires immediate medical attention.

Symptoms of DVT include:

• numbness or tingling sensation at the DVT location
• red or blue skin at the site of the DVT
• swollen or tender skin at the DVT location.

If you are experiencing any of the above DVT symptoms, contact your doctor immediately. Remember, however, that the majority of DVT sufferers experience no symptoms.

Before the MRI Procedure

The MRI procedure is fairly simple and generally lasts less than one hour. Most MRI scans are performed on an outpatient basis, meaning a hospital stay is generally not required.

In preparation for your MRI, you will need to remove all jewelry and accessories, as they can interfere with the MRI magnetic field. Also, you will likely need to remove your clothing and put on an examination gown.

Although your doctor may ask you to avoid food or drink for a specified period of time before your MRI, you can still follow your normal daily routine.

How Does an MRI Work?

MRIs produce images of internal body structures by directing radio waves at protons (the nuclei of hydrogen atoms) in a strong magnetic field, which is produced by passing an electric current through wire coils in the MRI units.

When a patient is positioned inside an MRI unit, the MRI technician directs radio waves at the protons in the area of the body that is being examined. As a result, the protons change their position in the magnetic field, producing signals that are detected by the coils.

A computer processes these signals and generates a series of images, each of which shows a thin slice of the body. Once all the images are taken, the computer can compile them into a 3-D representation of the area being studied. Your doctor will be able to examine these images from many different angles on the computer monitor.

The MRI Procedure: What to Expect

During your MRI, you can expect the following:

• After changing into your gown and removing all jewelry and accessories, you will be positioned on a mobile examination table. The MRI technician may use straps and/or other equipment to help you stay in the correct position during the procedure.
  
  
• Next, the MRI technician may need to place small devices that contain coils near the area of your body that is being scanned. These coils can send and receive radio waves.
  
  When using an MRI to diagnose DVT, the MRI technician or a nurse will need to inject an IV into your arm or hand. This will administer a saline solution into your veins until a contrasting solution is administered.
  
  
• After inserting the IV, your table will be moved into the magnet of the MRI unit. The traditional MRI unit is a cylinder-shaped tube that is surrounded by a magnet. Open MRI units do not completely surround the person and are good for scanning claustrophobic or obese individuals.
  
  You will remain in the magnet area of the MRI unit until the procedure is complete.
  
  
• After completing a series of initial scans, the MRI technician or a nurse will administer the contrasting material into your IV. The contrasting material allows doctors to see clots on the MRI scan.
  
  
• After the contrasting agent is injected, the MRI technician will perform another series of scans.
  
  
• Once all of the scans are collected and reviewed to ensure clarity and accuracy, your MRI procedure is complete.

MRI Drawbacks

MRIs are an effective method of diagnosing DVT. However, while MRIs allow doctors to simultaneously inspect both legs, some drawbacks to this diagnostic procedure include the following:

• MRI equipment isn't always readily available in some areas.
• MRIs are expensive, which can be especially problematic for patients who do not have health insurance or who have inadequate insurance coverage.
• MRIs cannot be used on patients who have certain types of implants, including pacemakers.
• People who are very claustrophobic may not be willing to undergo an MRI. Luckily, however, open MRI machines can often solve this problem.

Making a DVT Diagnosis with MRI Images

Once you have completed your MRI, a radiologist analyzes your scans to check them for blood clots. He will report his findings back to your doctor. If DVT is diagnosed, your doctor will determine the proper method of treatment, which may include anticoagulants or surgery.

Resources

American Academy of Orthopaedic Surgeons (June 2001). Deep Vein Thrombosis. Retrieved August 24, 2007, from the American Academy of Orthopaedic Surgeons Web site: http://orthoinfo.aaos.org/fact/thr_report.cfm?Thread_ID=264.

Radiological Society of North America, Inc. (2007). Magnetic Resonance Imaging (MRI). Retrieved August 24, 2007, from the RadiologyInfo Web site: http://www.radiologyinfo.org/en/info.cfm?pg=bodymr&bhcp=1.