How often have you been to the doctor and after talking with you he/she prattles off a list of tests that you have no real idea what they are used for? Even with the attempts of your physician to explain why each test/study is being ordered, you still arent quite sure you have a full understanding. I wont go over all the types of tests that are used in medicine, which would be like trying to count individual grains of sand on the beach. I will however, cover 3 big ones that are commonly used for foot/ankle related problems: X-ray, MRI, and CT.Oh my!!
- Usually the first study ordered for foot/ankle pathologies.
- It is definitely the most basic AND cheapest.
- It uses charged particles that create an image as they are passed through a structure.
- Every object/body structure behaves differently to these charge particles.
- Certain structures readily absorb these particles are identified on the radiograph as a white structure (i.e. Bone, Metal, etc)
- Other structures (i.e. Muscle, Tendon, Ligaments) are easily penetrated by these charged particles and thus do not display an image on the film.
- Best used for identifying fractures AND joint pathologies
- Arthritic changes and joint dislocations can be visualized with standard x-ray
- Boney type tumors can also be identified with standard x-rays BUT further evaluation may need to be done by more advanced imaging types.
- NOTE: Certain types of soft tissue problems can be noticed (i.e. Gas/Air in the soft tissue, Calcifications of arteries, swelling, etc). If any further focus is needed, an MRI or CT is the next step.
MRI (Magnetic Resonance Imaging):
- It uses a magnetic field to excite and realign the ions/particles of the body tissues to help form an image.
- MRI has various types of images your physician will look through in determining the cause of your problem.
- Best used for non-boney types of pathology because it has a much better soft tissue contrast.
- An MRI has the ability to take sliced pictures of the body part in question, such as the foot/ankle, and in multiple planes.
- This detail allows your physician to take a very close look at the structures in question
- Boney changes can be seen on MRI
- For example, Osteomyelitis (Bone infection) can be identified. It is not diagnostic, but it provides your physician with the ability to see the extent of the infection.
- Bone tumors can be viewed in more detail
- MRI is best used for tendon and ligament injury.
- Soft tissue tumors and abscesses can be identified using MRI.
- It is more costly, but when X-rays do not provide the full view of the problem, the MRI is ready to go.
CT (Computed Tomography):
- Uses x-rays (radiation) to form a picture of cross sections of the human body.
- Like MRI, the cross sections are cut into predetermined slices that provide higher detail.
- CT like x-ray is best used for boney pathology in the foot/ankle.
- It provides greater detail of the extent of any major fracture that an x-ray cannot provide.
- It can even show a fracture that may not have been seen on x-ray.
- New technology allows a 3D image of the foot to be formed. Not truly necessary, but it is really cool to look at.
- Unlike MRI, it uses radiation to form the image.
- Probably the more expensive of the 3 types of imaging, but when necessary a very valuable weapon in your physicians arsenal.
This was not meant to be a detailed review of these types of imaging modalities. It was only meant to provide a brief glimpse into the reasoning why your physician may need to order one or two of these studies. As always, I encourage you to ask questions if you do not fully understand why something is being done. Knowledge is power and it is extremely important to you AND your physician that you play an active role in your healthcare.
If you have any foot/ankle related conditions that need some good old fashioned TLC, please contact Dr. Bowman at 713-467-8886.
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Tags: CT, Houston, Medical Procedures, MRI, Podiatry, X-ray