Bone scan is an imaging test that allows you to view bone disease and trauma. Doctors prescribe it for suspected cases of osteoporosis, fracture, bone cancer, arthritis or osteomyelitis. The procedure involves injecting a radioactive substance (radiopharmaceutical) into a vein and then taking pictures of the body with a special radiation-sensitive camera. Your doctor will discuss the results with you, but it is worth learning more to understand the results of a bone scan.
Steps
Part 1 of 3: Interpreting the Results of a Bone Scan
Step 1. Get a copy of the images
The doctor who specializes in reading the radiographic images (radiologist) will draw up a detailed report that will be explained to you by the family doctor in simple words - at least hopefully. Generally, the original images are delivered together with the report itself, but if this does not happen you can request them at the hospital.
- Remember that it is your right to have a copy or the original of the plates or CD-ROM containing the images. Usually, you do not have to pay any commission to receive it, since you have paid for the exam in full or the fee required by the National Health System.
- Bone scan is done to detect changes in bone metabolism - the process by which bone tissue is formed and recycled. This activity is completely normal, but if it is too intense or too little, it means that there is a problem.
Step 2. Recognize the bones in the images
Most bone scans are performed on the entire skeleton, but sometimes they are limited to the painful or injured area, such as the wrist or spine. For this reason, learn a little about the basic anatomy, especially the names of most of the bones analyzed during the exam. Do some research online or borrow a book from the city library.
- You don't have to learn physiology or anatomy in detail, but you should understand which bones the radiologist refers to in the medical report he made after the test.
- The bones that are most taken into consideration are the vertebrae (which make up the spine), the pelvis (iliac bones, ischium and pubis), the ribs, those of the wrist (carpal bones) and those of the legs (femur, tibia and fibula).).
Step 3. Locate the problem
Once you have an idea of the bones analyzed, you need to understand which side of the body they are on. It is often not easy to understand by simply looking at the images, but almost always there is a sign or writing that indicates whether it is the right or left side of the body. For this reason, look for words like left, right, front or back on the pictures to figure out which side of the body they refer to.
- Bone scan images can be taken frontally or posteriorly. By observing the skull you are able to often define the orientation, although not always.
- Sometimes the results do not show the words in full, but only the letters that make us understand the type of projection. English terms are usually used and you can then read L (left) for left, R (right) for right, F (front) for front or B (back) for rear.
Step 4. Look for the reference date
If you have undergone multiple bone scans over time, which is quite common when it is necessary to follow the progression of a disease or the alteration of the bones, you need to determine the date and time the image was taken by observing the 'label. First study the scintigraphy you originally did and then compare it with the most recent one, noting the changes. If you don't see many differences, it is likely that the disease has not gotten worse or improved.
- If you have osteoporosis, for example, your doctor will recommend that you have a scan every 12 to 24 months to monitor the progression of the disease.
- If an infection is suspected, images will be taken immediately after the radiopharmaceutical is injected and then again after 3-4 hours when the substance has settled in the bones. In this case we speak of a triphasic bone scan.
Step 5. Look for points of greatest radiographic opacity
The results of a bone scan are considered normal when the radiopharmaceutical spreads and is absorbed by the skeleton in a uniform manner; they are considered abnormal when darker spots and radiographic discrepancies are seen in the bones. These changes indicate places in the skeleton where the radiopharmaceutical has accumulated, which means that there may be tissue destruction, inflammation, fracture, or tumor growth.
- Diseases that cause bone breakdown are aggressive carcinomas, bacterial osteomyelitis and osteoporosis (leading to weakening of the bones and fractures).
- Some bones normally appear darker due to their increased metabolic activity. These include the sternum and some parts of the pelvis. Don't confuse this normal sign with disease.
- In some cases, such as lesions caused by multiple myeloma, there are no dark spots on the bone scan and computed tomography or positron emission tomography is needed to identify signs of this type of cancer.
Step 6. Look for areas of less radiographic opacity
The results of a bone scan are considered abnormal even when lighter areas are found. In this case, the bone tissue has absorbed less (or none) of the radiopharmaceutical than the surrounding one. The causes are to be found in a reduced metabolic activity and bone remodeling. In general, poorly radiopaque spots indicate reduced blood supply of varying etiology.
- Lytic lesions: are associated with multiple myeloma, bone cysts and certain infections; they show up as lighter areas.
- The cause could be poor circulation triggered by a blockage of blood vessels (atherosclerosis) or a benign tumor.
- Light and dark areas can be present simultaneously and represent different, albeit concurrent, problems and diseases.
- Even if the slightly radiodense points are to be considered an alteration, they generally indicate less serious pathologies than the darker points.
Step 7. Understand the results
The radiologist interprets the images of the bone scan and draws up a report. The primary care physician will then use this information and process it together with that obtained from other diagnostic studies and / or blood tests to make a diagnosis. Common diseases that lead to an abnormal bone scan are: osteoporosis, fractures, bone cancer, osteomyelitis, arthritis, Paget's disease (a bone disorder that causes the bones to thicken and soften) and avascular necrosis (death of bone from lack of blood supply).
- With the sole exception of avascular necrosis which is manifested by poorly radiopaque spots, all the other diseases mentioned above cause the formation of dark spots in the bone scan images.
- The dark spots that commonly indicate osteoporosis are seen in the upper thoracic spine (mid-back), hip and / or wrist joint. Osteoporosis causes fractures and bone pain.
- Radiographic thickening caused by cancer is possible anywhere on the skeleton. Bone cancer is often the result of another metastatic cancer, such as breast, lung, liver, pancreas, and prostate cancer.
- Paget's disease is identified with dark spots along the spine, pelvis and skull bones.
- Bone infections are more common in the legs, feet, hands and arms.
Part 2 of 3: Preparing for a Bone Scan
Step 1. Remove all jewelry and other metal objects
While no special preparation is required to undergo this procedure, you should still wear comfortable clothes that you can take off quickly and avoid putting on jewelry. In particular, you should leave metal jewelry and watches at home or take them off shortly before taking the exam, as they can skew your results.
- Just like any other imaging test, such as x-rays, any metal object on the body produces images that are lighter or darker than the surrounding areas.
- Tell your radiologist or technician if you have metal fillings or other implants of the same material in your mouth or body, so that they can take note and not confuse them with pathological signs.
- It is always a good idea to wear clothes that you can take off without difficulty, as you may need to wear a hospital gown.
Step 2. Tell your doctor if you are pregnant
It is important to inform healthcare professionals that you are expecting or may be expecting a baby, as exposure to the radiation emitted by the contrast fluid could harm the fetus. For this reason, bone scans are not often performed on pregnant or breastfeeding women - breast milk easily becomes radioactive and contaminates the baby.
- There are other diagnostic imaging tests that are far safer for pregnant women, such as MRI and ultrasound.
- Temporary osteoporosis is not uncommon in pregnant women who are malnourished, because the fetus is forced to absorb the minerals necessary for its development from the maternal bones.
Step 3. Do not take any medicines that contain bismuth
While you can eat and drink normally before the exam, let your doctor know about any medications you take, as it may interfere with the scan. For example, those that contain barium or bismuth alter test results and should be avoided, at least four hours before your appointment.
- Bismuth is found in many medicines such as Pylorid, Denol and many others.
- Bismuth and barium cause the formation of poorly radiodense areas in the scintigraphic images.
Part 3 of 3: Understanding the Risks
Step 1. Understand the risks related to radiation
The amount of radiopharmaceutical that is injected into a vein is not important, but it still produces radiation in the body for up to three days. These increase the risk of healthy cells turning into cancerous, so you need to weigh the pros and cons with your doctor before getting tested.
- It has been estimated that a bone scan does not expose the body to more radiation than a normal full radiograph and is still less than half of that emitted during a computed tomography.
- By drinking plenty of water and liquids immediately after the exam and in the following 48 hours, you can expel any trace of radiopharmaceutical left in the body.
- If you have to undergo the test while you are breastfeeding a baby, suck the milk with a breast pump for two or three days and throw it away so as not to harm your baby.
Step 2. Watch out for allergic reactions
Those related to contrast fluid are rare, but when they do occur they can also be fatal. In most cases, the reaction is mild and causes pain, inflammation at the injection site and a mild rash. In severe cases, an anaphylactic crisis occurs which manifests itself as a systemic allergic reaction with edema, breathing difficulties, hives and hypotension.
- Call your doctor right away if you show signs of an allergic response once you get home after the exam.
- The bones need between one and four hours to absorb the radiopharmaceutical, while most allergic reactions occur within half an hour of the injection.
Step 3. Pay attention to possible infections
There is a slight risk of infection or bleeding where the needle was inserted into a vein to inject the radioactive fluid. Infections develop over two days and cause pain, redness, swelling in the area of the sting. Call the doctor immediately if you notice these symptoms; a course of antibiotics may be necessary to eliminate the problem.
- The most prominent signs of infection are intense and throbbing pain, purulent discharge, numbness and tingling of the affected arm, fever and fatigue.
- Make sure your doctor or technician wipes your arm with an alcohol wipe before giving you the injection.
Advice
- Bone scan is done in the radiology or nuclear medicine ward of hospitals or diagnostic centers. You will need a referral from the family doctor.
- During the exam you are made to lie on your back and a camera moves slowly along the body taking pictures of all the bones.
- You must remain still during the entire procedure, otherwise the images will be blurry. It is also necessary to change position in the various stages of the exam.
- The whole body bone scan takes about an hour.
- If the test finds any abnormal spots, other tests are needed to define the cause.
