Quick answer: a bone scan (skeletal scintigraphy) is a nuclear medicine test that shows areas of unusual activity in your bones. A small amount of radioactive tracer is injected into a vein; then you wait, usually 2 to 4 hours, while it is absorbed by the bones, drinking extra water. The scan itself is painless: you lie still while a camera takes pictures. Plan for most of a day, although you can usually leave and come back during the wait. A doctor trained in nuclear medicine reads the images and sends a report to your doctor.
Bone scans are among the most common tests in nuclear medicine, and the most common question I get is «why do I have to come back later?» The answer is that the tracer needs time to settle into the bones. Here is how the day goes.
What a bone scan shows
A bone scan shows how active the bone is, not just its shape. Areas where bone is breaking down or rebuilding take up more tracer and appear brighter («hot spots»); areas with less activity appear darker. Because it detects changes at this level, a bone scan can often find problems much earlier than a regular x-ray.
Doctors use it to:
- find bone cancer or check whether cancer from elsewhere, such as the breast, lung or prostate, has spread to the bones
- find the cause of unexplained bone pain, such as persistent low back pain
- diagnose fractures not clearly seen on x-rays, such as stress fractures or some hip fractures
- find bone damage from infection (osteomyelitis) or conditions such as Paget disease
- pinpoint problems in complex areas such as the foot or spine, often followed by a CT or MRI
- monitor how bone problems respond to treatment
How to prepare
There is usually little preparation, and you can normally eat as usual.
- Tell the team about all your medications and supplements, allergies, recent illnesses and medical conditions.
- Bismuth or barium: tell them if you have taken a bismuth-containing medicine (such as Pepto-Bismol) or had an x-ray test with barium contrast in the past four days. Both can interfere with the results.
- Fluids: because you will be asked to drink a lot after the injection, some centers ask you to limit fluids for up to four hours before the test.
- Pregnancy and breastfeeding: always tell the team. See the breastfeeding section below.
- Clothing: leave jewelry at home; you may be asked to wear a gown.
- Bring something to do for the waiting time: a book, work or something to watch.
Step 1: The injection
A nuclear medicine technologist injects the tracer into a vein in your hand or arm. You may feel a slight pin prick and a cold sensation moving up your arm. Generally, there are no other side effects; allergic reactions are extremely rare and usually mild.
For a three-phase bone scan, often used to look for infection or certain injuries, pictures are taken during the injection and immediately afterward, then again a few hours later.
Step 2: The waiting time (2 to 4 hours)
The tracer takes 2 to 4 hours to circulate and bind to your bones. During this time:
- Drink four to six glasses of water, as instructed. This helps remove tracer that does not go to the bones, which makes the images clearer.
- Urinate often.
- Many centers let you leave and come back at your scan time. Ask before you go.
From the scanner room: [TU EXPERIENCIA: qué recomiendas hacer durante la espera, si los pacientes pueden irse a casa o a comer, y la importancia de beber agua según lo que tú ves en las imágenes.]
Step 3: The scan
- Empty your bladder right before the scan, so tracer in the urine does not block the view of the pelvic bones.
- You lie on your back on the table. The gamma camera heads are placed very close to your body, above and below you, without touching you; this is needed for good images. The camera itself gives off no radiation.
- The camera moves slowly along your body or takes images of specific areas. You may be asked to change position between images.
- Sometimes a SPECT scan is added, in which the camera rotates around you to create 3D images, and in some centers a CT is combined with it.
- Stay still while the images are taken. If you have bone or joint pain, tell the technologist so they can help you get comfortable.
Afterward, the technologist may take extra images to look more closely at an area. This does not necessarily mean something is wrong.
From the scanner room: [TU EXPERIENCIA: cuánto dura en tu servicio el rastreo de cuerpo entero y las imágenes adicionales o el SPECT, y cómo colocas a pacientes con dolor.]
Typical timeline for the day
| Stage | Typical time |
|---|---|
| Injection (with early images for a three-phase scan) | A few minutes; longer for three-phase |
| Waiting while the tracer is absorbed | Usually 2 to 4 hours |
| Whole-body scan | Often 30 to 60 minutes |
| Extra images or SPECT, if needed | Additional time |
| Total visit | Often 3 to 5 hours from injection to the end of the scan |
After the scan
You can usually return to your normal activities right away. The tracer loses its radioactivity over time and leaves the body in urine and stool in the first hours and days. Keep drinking water to help flush it out. The amount of radiation is so small that it is not a risk to people around you after the test.
Breastfeeding: RadiologyInfo advises breastfeeding mothers to use formula for one to two days after the scan and to discard breast milk during that time. Recommendations vary between guidelines, so ask your nuclear medicine team what applies to you. See [link: Radioactive Tracers Explained: Are They Safe?].
Results timeline
A radiologist or nuclear medicine physician reviews the images and sends a report to the doctor who ordered the scan. Many centers send the report within a few working days, and sooner if the scan is urgent, but timing varies. Your doctor will go over the results with you.
If you use an online patient portal, the report may appear there before your doctor has reviewed it. See [link: How Long Do Imaging Results Take?].
Understanding the results
- A normal scan shows tracer spread evenly through the skeleton.
- Hot spots show areas of increased bone activity. They can be caused by many things, including arthritis, old injuries, fractures, infection and cancer, so a hot spot is not a diagnosis by itself.
- Cold spots show areas with little tracer, which can also have several causes.
Because a bone scan is very sensitive but not very specific, an abnormal finding may need further tests, such as an x-ray, CT, MRI, blood tests or a biopsy. Some types of cancer do not show up on a bone scan.
Tips from the technologist
[TU EXPERIENCIA: 3-4 consejos propios. Ideas: ir con ropa sin metal, no llevar niños pequeños a la cita si no hay quien los cuide durante la espera, beber agua aunque no se tenga sed, avisar de prótesis o fracturas antiguas.]
Frequently asked questions
Is a bone scan painful?
No. Apart from the injection, it is painless. Lying still can be uncomfortable if you have bone or joint pain.
Why do I have to wait so long between the injection and the scan?
The tracer needs about 2 to 4 hours to travel through your body and settle in the bones. Scanning too early gives poor images.
Can I eat before a bone scan?
Usually yes. There is normally no fasting for a standard bone scan; follow your center’s instructions.
Am I radioactive after a bone scan?
Only slightly, for a short time. The amount is so small that it is not a risk to people around you.
Is a bone scan the same as a bone density scan?
No. A bone density scan (DEXA) is a low-dose x-ray that measures bone strength to check for osteoporosis. A bone scan uses a radioactive tracer to show bone activity. See [link: DEXA Scan: Bone Density Test Explained].
Can a bone scan detect cancer?
It can show whether cancer has spread to the bones and can find some bone cancers, but hot spots have many causes and some cancers do not show up.
This article is for general information and does not replace advice from your doctor or nuclear medicine team.