Guide to Bone Densitometry
Bone densitometry is a non-invasive procedure that is used to measure bone density. The procedure is done using bone densitometers machines. The test is often performed on the lower spine and hips.
Why Test for Bone Density?
Bone densitometry is often used to diagnose and track the treatment of osteoporosis. This is a condition that many women develop after going through menopause. It can also be used to cheek for the risk of developing fractures. A test may be required for individuals who have some of these conditions: women with a history of factures, post menopausal women who weigh less than 125 pounds, those with a thyroid condition, an individual with signs of osteoporosis, and patients suffering form liver disease, kidney disease, diabetes, or with a history of osteoporosis.
Equipment That Is Used
Bone densitometers machines consist of a central device and a peripheral device. The peripheral device is small and portable and is used to measure the density of a heel, wrist, or finger. The central device is larger and is used by hospitals to measure the density of the spine and hip. The procedure works by the machine sending two X-ray energy peaks. One is absorbed by the bones and one is absorbed by the soft tissues. The energy peak from the soft tissue is then subtracted from the total value. The value that is remaining is the patient’s bone mineral density.
During the exam with the central device, the patient will lie on the exam table, and during a hip exam the foot will be braced in a brace to rotate the hip inward. If it is a spine exam, the legs will be placed in a box to get a better image. Patients are asked to remain still so images aren’t blurry. If using the peripheral devices, the finger, hand, or foot is placed in the device and then the images are taken.
More about the Procedure
The procedure is performed as an outpatient procedure at a hospital. A radiology technologist usually does the procedure and the entire process only takes between 10 and 30 minutes. A radiologist, rheumatologist, or an endocrinologist then reads results. The physician will interpret the test and the results will have a T score and Z score. The T score will show the amount of the bone the patient has when compared to a younger adult of the same gender with optimal amounts of bone mass. A Z score will show the level of bone a patient has compared to individuals in the same age, size, and gender group. A very high or low Z score will require additional testing.
A physician will evaluate a patient’s medical history, in order to gain knowledge of the health status, along with any medications. A patient should inform the physician if he or she has a history of any medical conditions or allergies that are related to iodinated contrast, which can be used in the procedure.