Bone Density Scan (DXA or DEXA)
What is a Dual Energy X-ray Absorptiometry (DEXA) Scan?
A DEXA scan is an imaging technique that uses X-rays (two beams) differing in their energies aimed at bones to measure the strength of the bones and establish the risk of developing osteoporosis. One beam is absorbed by soft tissue and the other by the bones. The difference between the two is called a T-score and is used to calculate bone mineral density. The higher the bone loss, the lower the density of the bones. DEXA scans are also called bone densitometry scan.
Who is at Risk of Bone Loss?
You may be at risk of bone loss and develop osteoporosis if you are:
- Diabetic
- Smoker or consume excess alcohol
- Suffering from hyperthyroidism, rheumatoid arthritis or kidney disorders
- Take corticosteroids or anti-seizures medications
- Women aged 65 or older, men aged 70 or older
What Happens if Osteoporosis is Untreated?
Spine or hip fractures are the serious complications of untreated osteoporosis. You may also develop a hunched back due to weak bones of your spine.
Preparation before a DEXA Scan
There are no special preparations needed before a DEXA scan. Talk to your doctor about the medicines you are taking, particularly calcium supplements and those you should stop taking prior to the procedure. Inform your doctor if you suspect pregnancy or recently had a CT-scan.
DEXA Scan Procedure
The procedure is performed on an outpatient basis. The regions scanned are usually your hip or spine. The procedure involves the following steps:
- You wear a hospital gown and lie on your back (supine position) on an X-ray table.
- Your technician helps you to position your legs on the padded box or a wedge.
- A DEXA scanner takes images of your hip. You may be asked to hold your breath for a few seconds.
- The results obtained are used to calculate your bone density.
Results of DEXA Scan
T-score of -1.0 or above = Normal bone density
T-score between -1.0 and -2.5 = Low bone density
T-score of -2.5 or lower = Osteoporosis
Treatment of bone loss
Based on your T-score, your doctor decides your treatment which may include:
- Vitamin D supplements or other medications to strengthen bones
- Strengthening exercises and weight loss program if applicable
- Lifestyle changes
Advantages of DEXA Scan
The advantages of a DEXA scan include:
- It is highly accurate when compared to a normal X-ray.
- It is a simpler procedure compared to CT-scan or MRI.
- The amount of radiation you receive is low.
- The procedure is completed in less time.
Contraindications of DEXA Scan
Your doctor may not suggest a DEXA scan if you are pregnant or obese. Older patients may need other techniques similar to a DEXA scan such as lateral vertebral assessment (LVA) to minimize exposure to radiation.
