Bone Density Scan - Indications, Procedure, Results, Benefits, and Risks

Creator: Dr. Nikitha Narayanan
Published: 2022-09-07T15:10:00

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A bone density scan is a specialized X-ray technique that is used to measure bone strength. Read this article for more information.

Written by

Dr. Nikitha Narayanan

Medically reviewed by

Dr. Varun Chaudhry

September 7, 2022

What Is Bone Density Scan?

A bone density scan is a radiological diagnostic test that uses a low-dose X-ray to measure calcium and mineral content in the bone. This measurement aids in determining bone strength or bone mass. It is also known as dual-energy X-ray absorptiometry (DEXA or DXA) scan or most commonly known as bone densitometry. A bone density scan is considered the gold standard to assess bone loss in patients suffering from osteopenia and osteoporosis. Osteopenia indicates weak bone or low bone mass, whereas osteoporosis is a progressive disease where bones are brittle and can be easily fractured.

What Are the Risk Factors for Low Bone Density?

The following conditions can lead to bone loss, and consequently, a greater risk of fracture:

Smoking and excessive consumption of alcohol.
Consumption of fizzy drinks, hydrogenated oils, excessive salt, and excess vitamin A have also been known to weaken the bones.
Diet low in vitamins and calcium.
Age.
Hormonal changes.
Poor physical activity.
Certain medications such as steroids and hormone replacement drugs.
Certain medical conditions such as chronic kidney diseases, arthritis, and cancer.

Why Is Bone Density Scan Done?

It is most commonly used to diagnose osteopenia and osteoporosis.
In patients with a repeated history of fractures.
To monitor ongoing osteoporosis treatment.
It is often used as a screening test in post-menopausal women as they are more prone to osteoporosis.
Bone density tests may also be indicated in certain inflammatory bone diseases such as arthritis (rheumatoid and psoriatic arthritis) as they cause severe bone loss.
The DXA machine can also be used to screen the spine for vertebral fractures. This procedure is also known as vertebral fracture assessment (VFA).

It is strongly recommended in:

People over 50 years as they have an increased risk of developing osteoporosis.
Chain smokers.
Patients who are on medications like corticosteroids, anti-epileptic drugs, or thyroid replacement drugs.

Patients with clinical conditions such as chronic kidney disease, liver disease, hyperthyroidism, type 1 diabetes, and hyperparathyroidism.
People with a family history of osteoporosis.
Women who had early menopause (before 45).

What Are the Benefits of Bone Density Scan?

Quick, non-invasive, and painless.
More effective than X-ray; for identifying even minute reductions in bone density.
Safe as lower levels of radiation are used when compared to conventional X-rays.
It is widely available, thus making it convenient for patients as well as physicians.

What Preparations Are Needed Before the Procedure?

DEXA scan does not require any special preparations.
Patients can follow their routine diet.
They would be advised to stop calcium supplements, multivitamins, and antacids, 24 to 48 hours before the test.
Patients will be advised to wear loose, comfortable clothing.
Avoid clothes with metal fasteners, zippers, buttons, and metal hooks.
Objects such as keys and wallets should also be avoided.
Any jewelry, eyeglasses, removable dental appliances, and other metallic objects should be removed before the procedure.
Female patients should inform the doctor if they think they might be pregnant.
Patients should also inform the doctor if they had a contrast CT (computed tomography) scan, a barium test, or any nuclear medicine test, as contrast material interferes with the bone scan.

How Is a Bone Density Scan Carried Out?

A bone density scan is usually performed as an outpatient procedure.
The entire procedure might take 10 to 30 minutes, depending on the part that is scanned.

What Are the Types of Dexa Scan?

There are two types of DEXA scan:

Central DEXA:

Bone density of the hip and spine are measured.
The patient will be asked to lie on their back on the X-ray table.
The patient will be advised to lie very still to get clear images.
A scanning machine, also known as an X-ray generator, passes beneath the patient.
At the same time, another scanning machine or the image detector will pass over the patient.
As the detector passes over the concerned area, images are generated and transferred to the computer.

The radiologist will view the image and interpret the results.

Peripheral DEXA:

Bone density of finger, hand, foot, heel, and forearm is usually measured. Ideally, a portable scanner is used.

How Are the Results Interpreted?

1. The results will be interpreted by the radiologist. The report should be discussed with the concerned physician, who can also assess the presence of any risk factors.2. The test results are available in the form of two scores; 1. T score and 2. Z score.3. T score is the bone density measurement in comparison to the bone density of healthy young adults of the same gender, age, and ethnicity. The scoring is as below:

-1 or above: Normal.
-1.1 and -2.4: Low bone density (osteopenia).
-2.5 or below: Osteoporosis.

4. Z score is the bone density as compared to other people of the same age and gender. An extremely high or low Z score may indicate the need for additional medical tests.

What Instructions Should Be Followed After the Procedure?

A bone density scan is a relatively easy and painless procedure. The patient should be able to return to their normal activities immediately. Based on the results, the physician can guide the patients with further treatment, dietary changes, and lifestyle modification.

What Are the Limitations?

The scan can offer a relative risk but cannot be a confirmatory predictor for the occurrence of fracture.
Patients with previous spinal abnormalities, spinal fractures, or spondylosis can get a false result.
Peripheral DEXA devices are more expensive than central ones.
A bone density test can only determine the low mineral density but cannot identify the reason for the same.

What Are the Risks?

The risk of radiation exposure cannot be neglected. However, the radiation used is very minimal, and also the advantages of the test compensate for the associated risk.

Conclusion:

Bone density tests are considered the gold standard for diagnosing osteoporosis and osteopenia. DEXA scans are accurate for measuring bone density, which is crucial for good bone health. It helps physicians spot bone loss in people who might have no symptoms. Early diagnosis of bone loss will ensure prompt treatment, thereby preventing conditions like osteoporosis and fractures.

Frequently Asked Questions

1. How Long Does a Bone Density Scan Take?

A bone density scan is a diagnostic procedure that measures the amount of calcium and minerals in the bone using a low-dose X-ray. An X-ray detector inside the scanning arm counts the quantity of X-rays that have passed through the body. This data will be used to create an image of the scanned area. Depending on the part being scanned, the entire process could take anywhere from ten to 30 minutes.

2. What Happens During a Bone Density Scan?

During the bone density scan, a large scanning arm is passed over the body to measure bone density in the center of the skeleton. The area of the body being examined will be exposed to a narrow beam of low-dose X-rays as the scanning arm is slowly moved over it. An X-ray detector inside the scanning arm counts the quantity of X-rays that have passed through the body.

3. Is a Bone Density Test Painful?

A bone density scanning test is a quick and pain-free procedure. It is a radiographic diagnostic procedure that measures the amount of calcium and minerals in the bone using a low-dose X-ray. A person needs to lie on their back on a flat, open X-ray table and keep still during the scan to avoid blurred images.

4. Why Are Bone Density Tests Advised?

The most typical uses of a bone density scan are -
- To identify osteopenia and osteoporosis.
- To keep track of ongoing osteoporosis therapy.
- A screening test in post-menopausal women.
- Patients who have a history of repeated fractures.
- Screen the spine for vertebral fractures.
Additionally, because inflammatory bone diseases like arthritis (rheumatoid and psoriatic arthritis) cause severe bone loss, bone density tests may also be advised in these cases.

5. Does a Person Have to Avoid Coffee Before a Bone Scan?

Before a DEXA (dual-energy X-ray absorptiometry) scan, no special preparations are necessary. Patients may continue eating normally. Drink, eat, and take any prescribed medications as usual. However, they would be instructed to stop taking antacids, multivitamins, and calcium supplements 24 to 48 hours before the test. Patients will also be advised to dress comfortably in loose-fitting clothing.

6. What Bone Density Is Appropriate for Someone Between 25 to 30 Years of Age?

The bone mineral density (BMD) is determined by a bone densitometry test (DXA or DEXA scan). The average BMD of an adult of the same sex and race at peak bone mass is then compared to the person’s bone density (approximately age 25 to 30). The T score is the outcome.
- Normal bone density is a T score of -1 to +1.
- T scores between -1 and -2.5 signify osteopenia (low bone density).
- Bone density must be sufficiently low (T score -2.5 or lower) to be considered osteoporosis.

7. How to Increase Bone Density After 60?

- Calcium: Males and females up to 50 should consume 1,200 milligrams of calcium per day; those over 50 should consume 1,000 milligrams.
- Vitamin D: Take 600–800 international units (IU) of vitamin D each day.
- Exercise: 30 minutes of daily exercise can help build bone density and fend off osteoporosis. Yoga, tai chi, and even simple walking are weight-bearing exercises that help the body defy gravity and encourage the growth of bone tissue. Strength training strengthens bones by constructing muscles.
- Avoid Smoking: It accelerates the loss of bone.
- Drink Alcohol in Moderation: For women and men over 65, having more than one drink daily is harmful. For men 65 and younger, having two drinks daily is harmful.
- Protein: Incorporate lean protein sources into the diets, such as lentils, eggs, white meat, poultry, dairy, lean beef, shrimp, and soy.
- Maintain a Healthy Weight.

8. Are There Any Side Effects to Bone Scans?

Bone scans typically have no negative side effects. This is because the small amount of radioactive chemicals in the body will gradually lose its radioactivity due to radioactive decay. Additionally, it leaves the body over the course of about 24 hours through the urine.

9. Does Bone Density Have Any Effect on Body Weight?

Bone mineral density (BMD) is directly correlated with body weight. When menstruation or an eating disorder is absent, a low body mass index (BMI) is a significant risk factor for lower BMD. It indicates greater bone loss in older age and younger people. Contrarily, high body weight can result from obesity or increased physical activity, which raises BMD.

10. What Needs to Be Avoided Before a Bone Density Test?

- Avoid calcium supplements, multivitamins, and antacids 24 to 48 hours before the test.
- Avoid clothing with metal fasteners, buttons, or hooks.
- Remove jewelry, eyeglasses, dental appliances, and other metallic objects.
- Inform the doctor if there is a possibility of pregnancy.
- Inform the doctor if there have been recent contrast CT scans, barium tests, or nuclear medicine tests.

11. Who Should Get a Bone Density Scan?

- Post-menopausal women aged 65 and older.
- Men aged 70 and older.
- Individuals with known risk factors or medical conditions affecting bone health.
- Individuals who have experienced fragility fractures often.
- Individuals who are on certain medications (steroids) that can affect bone health.

12. At What Age Should Women Consider Getting a Bone Density Test?

Women who have not experienced any bone fractures and do not have additional risk factors for osteoporosis are typically recommended to undergo a bone density test at the age of 65. However, if one is post-menopausal in their 40s, it is likely that one may need the test earlier, potentially as early as the age of 50, based on individual risk factors for osteoporosis.

13. Can a Bra Be Worn for a Bone Density Scan?

It is recommended to avoid wearing a bra with metal clasps or underwires during a bone density test. The metal components in the bra can interfere with the scan and potentially affect the accuracy of the results. It is advisable to wear a loose-fitting, comfortable garment without any metal fastenings to ensure clear and accurate images during the test.

14. Can Bone Density Be Checked at Home?

Checking bone density at home is not possible without specialized equipment and medical supervision. It is important to consult a healthcare provider for accurate assessment using diagnostic tools like a DEXA or DXA scan. Self-assessment methods or home devices may not provide reliable results and should not be relied upon for bone density evaluation.

15. What Fruits Are Beneficial for Bone Health?

Certain fruits are beneficial for bone health due to their nutrient content. Oranges are rich in vitamin C, which supports collagen production and bone strength. Apples provide antioxidants and polyphenols that may contribute to bone health. Kiwi is a good source of vitamin C, vitamin K, and other nutrients important for bone health. Berries, grapes, and pineapple also offer nutrients and compounds that can support bone health.

16. Which Food Can Help Increase Bone Density?

Dairy products (for example, cheese, yogurt, milk, etc.), leafy green vegetables, fish and seafood, nuts and seeds, fortified foods, and beans and legumes are some examples of the kind of food that can help improve bone density and promote bone health. A balanced diet that incorporates these nutrient-rich foods is important for overall bone health.

17. Can Walking Improve Bone Density?

Studies have shown that density of the bone can be improved by walking, especially in weight-bearing bones like the hips, legs, and spine. Regular walking puts stress on the bones, stimulating the body to build new bone tissue and increase bone density. However, it is recommended to combine walking with a balanced exercise routine and a healthy diet for optimal bone health.

18. Is an MRI Scan the Same as a Bone Density Scan?

No, bone density scans and MRI scans are different diagnostic techniques. Bone density testing measures the mineral content and density of bones, while MRI scans provide detailed images of soft tissues, organs, and bones using magnets and radio waves. A bone density scan usually takes a few minutes to complete, while an MRI scan can take longer because of its complexity.

Sources

Dr. Varun Chaudhry

Radiodiagnosis

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