The last imaging technique we’ll discuss will be different
types of full body scans available, specifically used by podiatrists to
determine if bone infection is present.
A scan, either for bone or WBCs (white blood cells), is done
by injecting a very small amount of a specific type of radioactive dye into a
vein. This dye will then spread through
the body as the blood is pumped through all the bone, muscle and internal
organs. The dye contains a certain
substance that will bind to somewhere in the body. The dye for bone scans binds to bone that is
currently being remodeled. The dye for
WBCs will search out WBCs and bind to them.
The person is then scanned at different time intervals with a gamma
camera, which is able to detect where the most activity is concentrated. This can be very useful in diagnosing foot
conditions.
When it comes to podiatry, these scans are primarily useful
with diabetic patients. Diabetic
patients struggle with two conditions, osteomyelitis (bone infection) due to
ulceration, and Charcot Foot (a non-infected bone destructive process). These two conditions are sometimes difficult
to tell apart clinically. With infected
bone, both a bone and WBC scan will be positive, whereas only a bone scan will
be positive with Charcot. Bone scans can
give the podiatrist clues to which process if going on. Scans are generally cheap tests and readily
available.
A downside to bone scans is that they are not very
specific. There are many conditions that
will have a positive bone scan. A
fracture, infected bone, growth plates, arthritis etc. will all give positive
bone scans. So even if I suspect bone
infection, and the bone scan comes back as positive, I still have to perform
other tests to confirm my suspicions.
There could be another underlying condition giving the positive bone
scan test. This obviously limits their
usefulness. Some types of scans are technically difficult to perform, and
others are difficult to read. Scans also expose the patient to some
radiation, thus making it necessary to make sure these scans are not ordered
unless absolutely necessary.
Imaging techniques used by podiatrists are essential in
determining the source of patient’s complaints.
These techniques are very safe when used in the appropriate
situations.
